Tesis: "Green chemistry"

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Liu, Tao. "Chemoinformetics for green chemistry". Doctoral thesis, Linnéuniversitetet, Institutionen för naturvetenskap, NV, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-8634.

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This thesis focuses on the development of quantitative structure-activity relationship (QSPR) models for physicochemical properties, e.g., vapor pressure and partitioning coefficients. Such models can be used to estimate environmental distribution and transformation of the pollutants or to characterize solvents properties. Here, chemoinformatics was used as an efficient tool for modeling to produce safe chemicals based on green chemistry principles. Experimental determinations are only available for a limited number of the chemicals; however, theoretical molecular descriptors can be used for modeling of all organic compounds. In this thesis, we developed and validated a global and local QSPR model for vapor pressure of liquid and subcooled liquid organic compounds, in which perfluorinated compounds (PFCs) as outliers appeared in the model due to their molecular properties. Subsequently, after the update of the previous model, the vapor pressure of perfluorinated compounds (PFCs) for which no reliable experimental data are available was successfully predicted. At the same time, we used partitioning between n-octanol/water (Kow) and water solubility (Sw) to investigate the similarities and differences between linear solvation energy relationship (LSER) and partial least square projection to latent structures (PLS) models. Further, we developed QSPR model for prediction of melting points and boiling points of PFCs using multiple linear regression (MLR), PLS and associative neural networks (ASNN) approaches, meanwhile, the applicability domain of PFCs was also investigated. Experimental, semi-empirical and theoretical quantitative structure-retention relationship (QSRR) models were used to accurately predict retention factors (logk) in reversed-phase liquid chromatography (RPLC). These models are useful to characterize solvents for determination of the behavior and interactions of molecular structure and develop chromatographic methods. In both of QSPR and QSRR models using the PLS method, the first and second components captured main information which is related to van der Waals forces and polar interactions, and their results coincide with those from LSER. The results showed that the models of physicochemical properties and retention factors (logk) in chromatographic system can be successfully developed by the PLS method. PLS models were able to predict physicochemical properties of organic compounds directly from theoretical descriptors without prior synthesis, measurement or sampling. Further, the PLS method could overcome colinearity in data sets, and it is therefore a rapid, cheap and highly efficient approach

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2

Goei, Elisabeth Rukmini. "Using Green Chemistry Experiments to Engage Sophomore Organic Chemistry". Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1280437800.

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3

Omajali, Jacob B. "Novel bionanocatalysts for green chemistry applications". Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6260/.

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Desulfovibrio desulfuricans have been known to synthesize good catalysts in a number of industrially and environmentally relevant reactions but the underlying reasons and/or mechanisms for such catalysis have largely remained elusive. This study has shown that in addition to nanoparticle (NP) size, the catalytic properties of D. desulfuricans is hinged on several factors such as the textural surface of the bacterial support, binding mechanism to surface functional groups (amine, carboxyl, phosphoryl and sulfuryl groups) and the crystal structure of the resulting catalyst NPs. In this study, various characterization techniques: AFM, EDX, SEM, HAADF-STEM, HRTEM, XRD and XPS and catalytic hydrogenation of soybean oil. The concept of intracellular trafficking of palladium into the cells of both Gram-negative (Desulfovibrio desulfuricans) and Gram-positive (Bacillus benzeovorans) bacteria was pioneered against previously known extracellular NP deposition. The membrane integrity and membrane potentials of “palladized” cells (‘bio-Pd’) were found to be retained through flow cytometry analysis. Bio-supported bimetallic (bio-Pd/Pt) catalyst from D. desulfuricans and B. benzeovorans demonstrated comparable catalytic properties to a commercial catalyst (Ni-Mo/Al\(_2\)O\(_3\)) as a potential ‘green’ alternative. Generally, the extent of viscosity reduction was: 98.7% (thermal), 99.2% (bio-NPs) and 99.6% (Ni-Mo/Al\(_2\)O\(_3\)) below 1031 mPa.s of the feed heavy oil. Also the bimetallic bio-NPs produced an increment of ~2\(^o\) in API (American petroleum institute) gravity (~9.1\(^o\)) than monometallic (~7.6\(^o\)) on average while the API gravity using thermal was lower (6.3\(^o\)) while that of a commercial catalyst was 11.1\(^o\). Finally, the concept of tandem (one-pot) catalysis was pioneered as a potential platform for the remediation of chlorinated benzenes.

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4

Sivaswamy, Swetha. "Industrial applications of principles of green chemistry". Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44776.

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Cross-linked polyethylene has higher upper use temperature than normal polyethylene and is used as an insulating material for electricity carrying cables and hot water pipes. The most common method of inducing crosslinks is by reaction with silanes. After incorporation of silanes into polyethylene and upon hydrolysis with ambient moisture or with hot water, Si-O-Si crosslinks are formed between the various linear polyethylene chains. Industrially, this reaction is performed routinely. However, the efficiency of this reaction with respect to the silane is low and control of product distribution is difficult. A precise fundamental understanding is necessary to be able to manipulate the reactions and thus, allow for the facile processing of the polymers. Hydrocarbon models of polymers - heptane, dodecane - are being used to study this reaction in the laboratory. For the reaction, vinyltrimethoxysilane is used as the grafting agent along with di-tert-butyl peroxide as the radical initiator. MALDI, a mass spectrometric technique is used for the analysis of the product distribution after work-up. Advanced NMR techniques (COSY, HSQC, DEPT, APT, HMBC) are being conducted on the grafted hydrocarbon compounds to gain an in-depth understanding of the mechanism and regiochemistry of the grafting reaction. Scalable and cost effective methods to capture CO2 are important to counterbalance some of the global impact of the combustion of fossil fuels on climate change. The main options available now include absorption, adsorption and membrane technology. Amines, especially monoethanolamine, have been the most commercialized technology. However, it is not without disadvantages. House et al have investigated the energy penalty involved in the post-combustion CO2 capture and storage from coal-fired power plants and found that 15-20% reduction in the overall electricity usage is necessary to offset the penalty from capturing and storing 80% of United States coal fleet's CO2 emssions1. Novel non-aqueous amine solvents, developed by the Eckert Liotta group, react with CO2 to form ionic liquids. The ionic liquids readily desorb CO2 upon heating, regenerating the reactive amines and this cycle can be carried out multiple times. An iterative procedure is being adopted to develop amine solvents for CO2 capture. Thermodynamic information like reversal temperature and boiling point of the solvents are collected; they are then used to formulate structure property relationships which allow for new molecules to be engineered. On reaction with CO2, there is a sharp increase in viscosity which is unfavorable from a processing standpoint. Many approaches to mitigate and control viscosity are being studied as well. 1House et al, Energy Environ Sci, 2009, 2, 193-205

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5

Curia, Silvio. "Supercritical carbon dioxide for green polymer chemistry". Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/36325/.

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This thesis details novel research on the design of new approaches that might lead to a more sustainable polymer industry by combining the use of supercritical carbon dioxide, a commercially available immobilised enzyme and renewable monomers. First, the key themes explored in this thesis are outlined. Green polymer chemistry, biodegradable and renewable polymers, biocatalysts for polymerisations (i.e. enzymes) and supercritical carbon dioxide as a reaction medium for polymer synthesis and processing are introduced (Chapter 1). Then, the high-pressure equipment and characterisation techniques are detailed. The reaction vessel used extensively in this research work is meticulously described. The high-pressure fixed-volume view cell and the high-pressure rheometer are also detailed (Chapter 2). This chapter includes also the standard operating procedure (SOP) for each piece of equipment. In the first research chapter, the carbon dioxide-induced melting point depression of poly(e-caprolactone) is investigated; thorough rheometric studies are used to provide a rheological viewpoint to this phenomenon (Chapter 3). Shear-viscosity studies were performed in order to assess the advantages that high-pressure carbon dioxide could deliver for semi-crystalline polymer processing. Visual observations of the polymer plasticisation and comparisons with high-temperature studies are also shown. In the subsequent chapter, the development of a novel enzymatic low-temperature approach for the preparation of functional low molecular weight polyesters is detailed (Chapter 4). By exploiting the unique properties of supercritical carbon dioxide and an enzyme catalyst, polymerisations ordinarily conducted using metal catalysts in excess of 200 °C were successfully conducted at milder conditions. Functional molecules could be used to end-cap the chains, thus producing green telechelics. Then, this innovative synthetic approach was extended to the preparation of bio- based amphiphilic polymers, which could be useful for drugs encapsulation and as surfactants in detergent formulations (Chapter 5). Specifically, the self-assembly of these novel polymers and the stability of the aggregated structures in water were investigated in detail. Additionally, encapsulation of a highly lipophilic molecule (Coumarin-6) and surface tension studies provided a clear demonstration of the usefulness of these polymers for a wide range of applications. The final part of the thesis sums up the overall conclusions obtained from this research work and outlines possible opportunities for future research in this area (Chapter 6).

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6

Rahm, Martin. "Green Propellants". Doctoral thesis, KTH, Fysikalisk kemi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-25835.

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To enable future environmentally friendly access to space by means of solid rocket propulsion a viable replacement to the hazardous ammonium perchlorate oxidizer is needed. Ammonium dinitramide (ADN) is one of few such compounds currently known. Unfortunately compatibility issues with many polymer binder systems and unexplained solid-state behavior have thus far hampered the development of ADN-based propellants. Chapters one, two and three offer a general introduction to the thesis, and into relevant aspects of quantum chemistry and polymer chemistry. Chapter four of this thesis presents extensive quantum chemical and spectroscopic studies that explain much of ADN’s anomalous reactivity, solid-state behavior and thermal stability. Polarization of surface dinitramide anions has been identified as the main reason for the decreased stability of solid ADN, and theoretical models have been developed to explain and predict the solid-state stability of general dinitramide salts. Experimental decomposition characteristics for ADN, such as activation energy and decomposition products, have been explained for different physical conditions. The reactivity of ADN towards many chemical groups is explained by ammonium-mediated conjugate addition reactions. It is predicted that ADN can be stabilized by changing the surface chemistry with additives, for example by using hydrogen bond donors, and by trapping radical intermediates using suitable amine-functionalities. Chapter five presents several conceptual green energetic materials (GEMs), including different pentazolate derivatives, which have been subjected to thorough theoretical studies. One of these, trinitramide (TNA), has been synthesized and characterized by vibrational and nuclear magnetic resonance spectroscopy. Finally, chapter six covers the synthesis of several polymeric materials based on polyoxetanes, which have been tested for compatibility with ADN. Successful formation of polymer matrices based on the ADN-compatible polyglycidyl azide polymer (GAP) has been demonstrated using a novel type of macromolecular curing agent. In light of these results further work towards ADN-propellants is strongly encouraged.
QC 20101103

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7

Vallin, Karl S. A. "Regioselective Heck Coupling Reactions : Focus on Green Chemistry". Doctoral thesis, Uppsala University, Department of Medicinal Chemistry, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3380.

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Carbon-carbon bond formation reactions are among the most important processes in chemistry, as they represent key steps in the synthesis of more complex molecules from simple precursors. This thesis describes mainly the development of novel regioselective applications of the mild and versatile palladium-catalyzed carbon-carbon coupling method, commonly known as the Heck reaction. In addition, this thesis will focus on environmentally friendly developments of the Heck reaction.

Novel ligand-controlled internal Heck vinylations of vinyl ethers and enamides to form branched electron-rich dienes were performed with high regioselectivity. The vinylation of 2-hydroxyethyl vinyl ether permits a chemoselective transformation of a vinylic triflate or bromide into a blocked α,β-unsaturated methyl ketone. Furthermore, a simple separation of the palladium catalyst was achieved with new fluorous-tagged bidentate ligands in combination with fluorous solid phase extraction. The reaction times could be reduced up to 1000 times with controlled microwave heating in the palladium-catalyzed reactions with, in the majority of cases, retained, high selectivity.

The development of a “green” regioselective arylation and vinylation method relying on an aqueous DMF-potassium carbonate system and excluding the toxic thallium salt has been accomplished. Ionic liquids as the versatile and environmentally friendly class of solvents have been used in rapid phosphine-free terminal Heck arylations with controlled microwave heating. Recycling of the catalytic medium was achieved after a simple product purification.

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8

Arcelay, Angel R. "The free energy generated by photosystem I and photosystem II of green and blue-green algae /". The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487591658173946.

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9

Giménez, Pedrós Marta. "Towards green chemistry: alternative solvents for catalysed carbonylation reactions". Doctoral thesis, Universitat Rovira i Virgili, 2005. http://hdl.handle.net/10803/9076.

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L'objectiu d'aquest treball ha estat l'estudi de l'ús de dissolvents alternatius no tòxics, com l'aigua i el diòxid de carboni supercrític, en les reaccions catalitzades d'hidroformilació i copolimerització. En el capítol 3 s'estudia la hidroformilació de 1-octè i 1-decè en medi aquós utilitzant catalitzadors de rodi associats a les difosfines sulfonades dpppts i dppbts. Per tal d'augmentar la solubilitat d'aquestes olefines en l'aigua es van utilitzar diferents estratègies com l'ús de co-solvents, tensioactius i una macromolècula dendrimèrica, com a agents de transferència de fase. L'addició del tensioactius aniònics al sistema augmenta la conversió del sistema en ambdós substrats malauradament la selectivitat en aldehids va ser baixa. L'addició del tensioactiu catiònic va augmentar tant la conversió com la selectivitat en aldehids. En aquest cas el sistema catalític es va poder reciclar mantenint tant la activitat com la selectivitat. L'addició de metanol com a co-solvent emprant 1-octè com a substrat va resultar en un augment de la conversió. L'addició del dendrimer al sistema no va millorar els resultats obtinguts.
El diòxid de carboni supercrític (scCO2) també s'ha estudiat com a medi de reacció. En el capítol 4 es descriu la síntesis de tres lligands fòsfor-dadors nous que contenen cadenes ramificades, PPh3-n(OC9H19) (n = 1, 2, 3), amb l'objectiu d'utilitzar-los en la reacció d'hidroformilació de 1-octè utilitzant com a dissolvent scCO2. Per tal d'estudiar la química de coordinació d'aquests lligands es van sintetitzar complexos catiònics de Rh(I) i complexos neutres de pal·ladi (II). Per mitjà d'estudis de ressonància magnètica i espectroscòpia infraroja a pressió es van estudiar les espècies que es formen en les condicions de hidroformilació. Els lligands sintetitzats no van donar lloc a sistemes catalítics solubles en scCO2 en les condicions estudiades. Malgrat això aquests sistemes van ser actius per la reacció d'hidroformilació de 1-octè en scCO2 i toluè. En condicions apropiades de reacció s'obtenen conversions i selectivitats elevades en ambdós solvents. Amb el sistema Rh/PPh2(OC9H19) emprant scCO2 com a dissolvent es va obtenir una millora de selectivitat en aldehids.
En el capítol 5 es descriu l'aplicació del lligand P(C6H4-p-OCH2C7F15)3 a la reacció d'hidroformilació de 1-octè,1-decè i estirè catalitzada per rodi. Aquests sistema va resultar soluble en scCO2. Emprant baixes concentracions de rodi i una relació P:Rh = 3, es van observar bones activitats i selectivitats en aldehids per a la hidroformilació d'1-octè. El sistema també va resultar actiu per la hidroformilació d'1-decè i estirè.
La reacció de copolimerització d'alquens i monòxid de carboni catalitzada per pal·ladi permet la síntesi de policetones. Per a la copolimerització de tert-butilestirè i CO, un dels sistemes més actius està basat en l'ús de catalitzadors de pal·ladi amb lligands N-dadors: bipiridina i fenantrolina. En el capítol 6 es descriu el primer exemple de copolimerització de tert-butilestirè i monòxid de carboni catalitzada per sistemes de pal·ladi emprant com a medi de reacció el diòxid de carboni supercrític. Per assolir aquest objectiu es van sintetitzar lligands bipiridina i fenantrolina amb cadenes perfluorades per tal d'augmentar la solubilitat del sistema catalític en scCO2. Es van sintetitzar els complexos neutres de pal·ladi [PdCl(CH3)(Bipif o Phenf)] i els complexes catiònics de pal·ladi [Pd(CH3)(NCCH3)(Bipif o Phenf)]BARF. Els complexos catiònics de pal·ladi van mostrar una elevada solubilitat en scCO2. La reacció de copolimerització de tert-butilestirè i CO es va estudiar tant en scCO2 com en diclormetà com a dissolvents. Els resultats van mostrar que el sistema catalític presenta una activitat similar en diòxid de carboni supercrític a la que s'observa amb diclormetà però en el medi supercrític els copolímers tenen pesos moleculars que arriben a ser el doble del que s'obté en el dissolvent orgànic i amb polidispersitats molt més baixes.
The main objective of this thesis was to study the use of alternative and non-toxic solvents, water and supercritical carbon dioxide, for catalysed hydroformylation and copolymerisation reactions. Rhodium catalysed hydroformylation of 1-octene and 1-decene in biphasic aqueous systems using sulfonated diphosphines (dpppts, dppbts) as ligands was studied in Chapter 3. In order to increase the solubility of the alkenes in water different strategies such as addition of surfactants, co-solvents and a dendrimeric molecule have been studied. The addition of an anionic surfactant to both systems increases the conversion but the selectivity in aldehydes decreases obtaining mainly isomers as reaction products. The addition of a cationic surfactant to the system increases both activity and selectivity in aldehydes. However, high concentrations of cationic surfactants led to loss of catalyst in the organic phase. When 1-octene was used as substrate a slight increase in regioselectivity in nonanal was observed. Using 1-decene and dppbts a ligand high selectivity in aldehydes up to 97% with 63% of conversion were obtained, in addition the system could be recycled maintaining both conversion and selectivity in aldehydes. The addition of methanol as a co-solvent increases the conversion of the reaction, when dppbts was used as a ligand an enhancement in aldehydes selectivity was observed. The use of dendrimer did not improve the results.
In Chapter 4 was studied the hydroformylation of 1-octene in supercritical carbon dioxide. In order to obtain soluble catalyst in supercritical carbon dioxide new ligands containing alkyl chains, PPh3-n(OC9H19)n (n = 1, 2, 3), were synthesised. The coordination of these ligands to rhodium and palladium, the activity of these ligands in hydroformylation of 1-octene in toluene as a solvent and the reactivity of them with CO/H2 were also discussed. Although the ligands were not soluble in scCO2, good activities can be obtained using the appropriate reaction conditions, similar conversion and aldehydes selectivity than the obtained using toluene as a solvent where obtained using P(OC9H19)3 as a ligand. Using PPh(OC9H19)2 and PPh2(OC9H19) as ligands in supercritical carbon dioxide low conversion were observed. However improved selectivities in aldehydes were obtained.

Chapter 5 deals with the use of perfluorinated ligands in order to solubilize the catalyst in supercritical carbon dioxide. A perfluorinated phosphine previously applied to biphasic fluorous hydroformylation was used to study the catalyzed rhodium hydroformylation of 1-octene, 1-decene and styrene in scCO2. The solubility studies showed that the catalytic system was soluble in supercritical carbon dioxide. Good activities and selectivities in aldehydes using 1-octene as a substrate were observed at very low rhodium concentrations and P:Rh ratios.

In Chapter 6 was studied the copolymerisation of 4-tert-butylstirene with CO in supercritical carbon dioxide. To achieve this objective we propose the synthesis of N-donor ligands containing perfluorinated chains. The neutral palladium complexes [PdCl(CH3)(Bipyf o Phenf)] and cationic palladium complexes [Pd(CH3)(NCCH3)(Bipyf o Phenf)]BARF were synthesised. The cationic complexes showed high solubility in supercritical carbon dioxide. These complexes were used as catalysts in the palladium catalysed copolymerisation of 4-tert-butylstirene with CO using scCO2 and dichloromethane as solvents. The results obtained showed that the catalytic system has similar activities in both solvents. However, using carbon dioxide as a solvent the molecular weights are higher than the obtained in dichloromethane in the same reaction conditions. Moreover the polyketones obtained in scCO2 have very narrow molecular weight distribution.

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10

Kopetzki, Daniel. "Exploring hydrothermal reactions : from prebiotic synthesis to green chemistry". Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5258/.

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In this thesis chemical reactions under hydrothermal conditions were explored, whereby emphasis was put on green chemistry. Water at high temperature and pressure acts as a benign solvent. Motivation to work under hydrothermal conditions was well-founded in the tunability of physicochemical properties with temperature, e.g. of dielectric constant, density or ion product, which often resulted in surprising reactivity. Another cornerstone was the implementation of the principles of green chemistry. Besides the use of water as solvent, this included the employment of a sustainable feedstock and the sensible use of resources by minimizing waste and harmful intermediates and additives. To evaluate the feasibility of hydrothermal conditions for chemical synthesis, exemplary reactions were performed. These were carried out in a continuous flow reactor, allowing for precise control of reaction conditions and kinetics measurements. In most experiments a temperature of 200 °C in combination with a pressure of 100 bar was chosen. In some cases the temperature was even raised to 300 °C. Water in this subcritical range can also be found in nature at hydrothermal vents on the ocean floor. On the primitive earth, environments with such conditions were however present in larger numbers. Therefore we tested whether biologically important carbohydrates could be formed at high temperature from the simple, probably prebiotic precursor formaldehyde. Indeed, this formose reaction could be carried out successfully, although the yield was lower compared to the counterpart reaction under ambient conditions. However, striking differences regarding selectivity and necessary catalysts were observed. At moderate temperatures bases and catalytically active cations like Ca2+ are necessary and the main products are hexoses and pentoses, which accumulate due to their higher stability. In contrast, in high-temperature water no catalyst was necessary but a slightly alkaline solution was sufficient. Hexoses were only formed in negligible amounts, whereas pentoses and the shorter carbohydrates accounted for the major fraction. Amongst the pentoses there was some preference for the formation of ribose. Even deoxy sugars could be detected in traces. The observation that catalysts can be avoided was successfully transferred to another reaction. In a green chemistry approach platform chemicals must be produced from sustainable resources. Carbohydrates can for instance be employed as a basis. They can be transformed to levulinic acid and formic acid, which can both react via a transfer hydrogenation to the green solvent and biofuel gamma-valerolactone. This second reaction usually requires catalysis by Ru or Pd, which are neither sustainable nor low-priced. Under hydrothermal conditions these heavy metals could be avoided and replaced by cheap salts, taking advantage of the temperature dependence of the acid dissociation constant. Simple sulfate was recognized as a temperature switchable base. With this additive high yield could be achieved by simultaneous prevention of waste. In contrast to conventional bases, which create salt upon neutralization, a temperature switchable base becomes neutral again when cooled down and thus can be reused. This adds another sustainable feature to the high atom economy of the presented hydrothermal synthesis. In a last study complex decomposition pathways of biomass were investigated. Gas chromatography in conjunction with mass spectroscopy has proven to be a powerful tool for the identification of unknowns. It was observed that several acids were formed when carbohydrates were treated with bases at high temperature. This procedure was also applied to digest wood. Afterwards it was possible to fermentate the solution and a good yield of methane was obtained. This has to be regarded in the light of the fact that wood practically cannot be used as a feedstock in a biogas factory. Thus the hydrothermal pretreatment is an efficient means to employ such materials as well. Also the reaction network of the hydrothermal decomposition of glycine was investigated using isotope-labeled compounds as comparison for the unambiguous identification of unknowns. This refined analysis allowed the identification of several new molecules and pathways, not yet described in literature. In summary several advantages could be taken from synthesis in high-temperature water. Many catalysts, absolutely necessary under ambient conditions, could either be completely avoided or replaced by cheap, sustainable alternatives. In this respect water is not only a green solvent, but helps to prevent waste and preserves resources.
In dieser Arbeit wurden chemische Reaktionen unter Hydrothermalbedingungen untersucht. Darunter versteht man Wasser als Reaktionsmedium, welches eine Temperatur über 100 °C aufweist. Der flüssige Zustand wird dabei durch erhöhten Druck aufrecht erhalten. Typischerweise wurden die Reaktionen bei 200 °C und einem Druck von 100 bar durchgeführt, also dem 100-fachen des Normaldrucks. Dieses System kann man auch mit einem Dampfdrucktopf vergleichen, wobei durch die erhöhten Temperaturen chemische Reaktionen sehr schnell ablaufen und überraschende Reaktivität auftritt. Die Motivation, Wasser als Lösemittel zu benutzen, ist auch in seiner Umweltfreundlichkeit gegenüber klassischen organischen Lösemitteln begründet. Da solche Hydrothermalbedingungen auf der frühen Erde häufiger anzutreffen waren, wurde untersucht, ob wichtige Biomoleküle bei solch hoher Temperatur gebildet werden können. In der Tat konnten Zucker aus der sehr einfachen Verbindung Formaldehyd synthetisiert werden. Hierzu war lediglich eine leicht basische Lösung nötig und keine der bei moderaten Temperaturen essentiellen Katalysatoren. Zucker stellen zudem den größten Teil der pflanzlichen Biomasse dar und können daher als Grundlage für eine nachhaltige Chemie dienen. Sie können relativ einfach zu Lävulin- und Ameisensäure umgesetzt werden. Aus diesen wiederum kann die wichtige Basischemikalie gamma-Valerolacton hergestellt werden. Der Schlüsselschritt, die Reduktion von Lävulinsäure, erforderte bisher die Zuhilfenahme seltener Edelmetalle wie Ruthenium. Es konnte nun gezeigt werden, dass unter Hydrothermalbedingungen diese Rolle von einfachen Salzen, z. B. Natriumsulfat, übernommen werden kann. Hierbei macht man sich zunutze, dass sie nur bei hoher Temperatur basisch wirken, nicht aber wenn die Lösung wieder abgekühlt ist. Neben Kohlenhydraten besteht Biomasse auch aus Aminosäuren, von denen Glycin die einfachste darstellt. Unter Abspaltung von CO2 können aus ihnen synthetisch wichtige Amine hergestellt werden. Diese Reaktion findet unter Hydrothermalbedingungen statt, daneben treten jedoch noch andere Produkte auf. Unbekannte Verbindungen wurden mittels Massenspektroskopie identifiziert, wobei die Masse des Moleküls und bestimmter Molekülfragmente bestimmt wurde. Dies erlaubte es, bisher noch unbekannte Reaktionswege aufzuklären. Zusammenfassend lässt sich sagen, dass Wasser unter Hydrothermalbedingungen eine interessante Alternative zu organischen Lösemitteln darstellt. Desweiteren können bestimmte Katalysatoren, die bei moderaten Temperaturen nötig sind, entweder vollständig eingespart oder ersetzt werden. In dieser Hinsicht ist Wasser nicht nur ein umweltfreundliches Lösemittel, sondern trägt dazu bei, Abfall zu vermeiden und Ressourcen zu schonen.

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11

McGregor, Stuart Thomas. "Clean green chemistry : enzyme-catalysed and chemical asymetric synthesis". Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485058.

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Chapter 1 provides an introduction to the metabolism of aromatic compounds by enzymes, and the use of bioproducts in synthesis. A brief introduction into the synthesis and potential applications of amino alcohols is also discussed. Finally, a summary of a number of methods for the-determination of enantiomeric excess concludes the chapter. Chapter 2 investigates the synthesis oftrans-dihydrodiols from their cis-dihydrodiol precursors. The desymmetrisation ofmeso-l,2-dihydroxycyclohexane is also discussed. The chemoenzymatic synthesis oftrans-I,2-aminocyclohexanols, including the biologically important compound vesamicol is examined. Chapter 3 explores the synthesis of a number ofcis- and trans-azido alcohols from bromo- and chIoro- benzene, and the conversion ofthe azido alcohols to cis- and trans-amino alcohols. A brief investigation into the substitution ofthe halide atom in bromobenzene-cis-diol is discussed as a potential route to a library ofcis- and (rmlS- amino alcohols. Chapter 4 is divided into three parts. The first section discusses a number of synthetic routes to vicinal cis- and trmls- amino alcohol derivatives of naphthalene. The second section outlines the bacterial metabolism ofselected polycyclic aromatic hydrocarbons and the formation of bis-cis-diols. The final section introduces a new class of bacterial metabolites from acetonide-protected diol substrates.

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12

Dahl, Jennifer Ann. "Synthesis of functional nanomaterials within a green chemistry context /". Connect to title online (Scholars' Bank) Connect to title online (ProQuest), 2007. http://hdl.handle.net/1794/6131.

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Thesis (Ph. D.)--University of Oregon, 2007.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 158-183). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.

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13

Raynel, Guillaume. "Application of green chemistry principles to the pharmaceutical industry". Thesis, University of Leeds, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.553778.

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Olsen, Sarah. "Synthesis of Copper Sulphides: A Green Chemistry Microwave Approach". Thesis, KTH, Tillämpad fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279452.

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15

Roberts, Jody Alan. "Creating Green Chemistry: Discursive Strategies of a Scientific Movement". Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/27529.

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In this dissertation, I examine the evolution of the green chemistry movement from its inception in the early 1990s to the present day. I focus my study on the discursive strategies employed by leaders of the movement to establish green chemistry and to develop and institute changes in the practice of the chemical sciences. The study looks specifically at three different strategies. The first is the construction of a historical narrative. This history comes from the intersection of the chemical sciences with environmentalism in the United States retold to place chemistry in a central position for understanding global environmental health issues and green chemistry as the natural response to these problems. The second involves the attempts made to develop a concrete definition for green chemistry as well as a set of guiding principles for the practice of this alternative form of chemistry. The establishment of the definition and the principles, I argue, constitutes an important move in constituting the field as a very specific interdisciplinary group with a forged identity and the beginnings of a system for determining what properly â countsâ as green chemistry. The third comes from the intersection of this history within the defining principles of the movement intersect to create a specific set of green chemistry practices, and how these practices manifest themselves in conference and pedagogical settings. Finally, I offer an overview of where the movement currently stands, offering a critical perspective on the future potential of the field. I argue that recent episodes indicate that the movement has not succeeded in accomplishing what it set out to do, and will continue to encounter problems unless a refashioning of the movement takes place. To offer perspective on green chemistry as a movement, I examine it through the lens of other (e.g., Frickel and Gross 2005) attempts to explore scientific movements as a special class of social movements.
Ph. D.

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16

Sen, Mustafa Yasin. "Green Polymer Chemistry: Functionalization of Polymers Using Enzymatic Catalysis". University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1258422775.

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17

Stanley, Jessica. "Novel applications of catalysis for green and sustainable chemistry". Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/12679.

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This thesis examines fundamental studies of catalysts for more sustainable processes, addressing three particular challenges: (1) Developing sulfur resistant catalysts that have potential applications in the processing of biomass for the production of liquid transportation fuels. (2) Reducing energy requirements and increasing the catalyst ease-of-use (especially water tolerance) for the hydrogenation of aromatics, particularly for the safe and feasible storage of hydrogen using the reversible toluene/methylcyclohexane couple. (3) Catalytically converting models of lignin building blocks as a source for renewable aromatic chemicals.

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18

Dahl, Jennifer Ann 1976. "Synthesis of functional nanomaterials within a green chemistry context". Thesis, University of Oregon, 2007. http://hdl.handle.net/1794/6131.

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xvii, 183 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.
In recent years, nanoscience has evolved from a multidisciplinary research concept to a primary scientific frontier. Rapid technological advancements have led to the development of nanoscale device components, advanced sensors, and novel biomimetic materials. However, potential negative impacts of nanomaterials are sometimes overlooked during the discovery phase of research. The implementation of green chemistry principles can enhance nanoscience by maximizing safety and efficiency while minimizing the environmental and societal impacts of nanomaterials. This dissertation introduces the concept of green nanosynthesis, demonstrating the application of green chemistry to the synthesis of nanornaterials. A comprehensive review of the synthesis of metal nanomaterials is presented, demonstrating how individual green chemistry principles can improve traditional synthetic routes as well as guide the design of new materials. Detailed examples of greener syntheses of functionalized gold nanoparticles with core diameters of 2-10 nm are described in subsequent chapters, beginning with a method for functionalizing citrate-stabilized gold nanoparticles that are desirable for advanced applications. Although citrate-stabilized gold nanoparticles can be easily produced from a classic procedure using mild reagents and benign methods, functionalization via ligand exchange is often unsuccessful. It was discovered that an ill-defined layer comprised of citrate and other ligands interferes with functionalization processes. By removing excess citrate in a manner where overall structure and stability is maintained, gold cores produced by this route are readily functionalized by incoming thiols, affording unprecedented control over surface composition and functionality. A direct route to functional nanomaterials using Bunte salt precursors is discussed next, describing the use of easily synthesized shelf-stable alternatives to thiols in the preparation of water-soluble gold nanoparticles. Control of core size and surface chemistry is demonstrated through simple manipulation of reagent ratios, yielding products similar to those produced by traditional direct syntheses which rely on the use of thiols. The use of functionalized nanoparticles as "building blocks" for more complex structures was demonstrated in self-assembly processes. Cationic gold particles were deposited upon DNA scaffolds to create linear arrays. A discussion of the future outlook of green nanosynthesis concludes this work, identifying immediate challenges and long-term goals. This dissertation contains previously published and co-authored materials.
Adviser: James E. Hutchison

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19

Stanley, Jessica Nicole Gonzalo <1987&gt. "Novel applications of catalysis for green and sustainable chemistry". Doctoral thesis, Università Ca' Foscari Venezia, 2014. http://hdl.handle.net/10579/5655.

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This thesis examines fundamental studies of catalysts for more sustainable processes, addressing three particular challenges: (1) Developing sulfur resistant catalysts that have potential applications in the processing of biomass for the production of liquid transportation fuels. (2) Reducing energy requirements and increasing the catalyst ease-of-use (especially water tolerance) for the hydrogenation of aromatics, particularly for the safe and feasible storage of hydrogen using the reversible toluene/methylcyclohexane couple. (3) Catalytically converting models of lignin building blocks as a source for renewable aromatic chemicals.

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20

Mehta, Brinda Mayank. "Green Resins based on Alkene- and Alkyne-containing Triglycerides". University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1468795161.

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21

Mdoe, James Epiphan Gabriel. "Organically modified mesoporous silicas as base catalysts for green chemistry". Thesis, University of York, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310988.

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22

OLIVEIRA, BERNADETE FERREIRA DE. "GREEN ANALYTICAL CHEMISTRY: CONTRIBUTIONS TO THE PUC-RIO’S ENVIRONMENTAL AGENDA". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2012. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=20268@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
O objetivo da dissertação é avaliar o potencial do Departamento de Química da PUC-Rio de desenvolver e adotar métodos de Química Analítica Verde, tendo em vista a inserção de um conjunto de ações no escopo da Agenda Ambiental PUC-Rio. No contexto institucional no qual a pesquisa se insere, considera-se que os resultados desta pesquisa terão um grande potencial de aplicação em diversos departamentos da PUC-Rio, em particular no Departamento de Química. Poderá servir de embrião ou estímulo para a proposição de um conjunto de ações que contribuirão para o enriquecimento e materialização da Agenda Ambiental PUC – Rio. Quanto aos fins, a pesquisa pode ser considerada aplicada e descritiva. Quanto aos meios de investigação, a metodologia compreende pesquisa bibliográfica e documental, pesquisa de campo, com entrevistas semi-estruturadas e estudo de caso. Destacam-se como resultados: (i) mapeamento das metodologias analíticas que estão sendo desenvolvidas e empregadas em nível mundial e que vêm contribuindo para o avanço da Química Analítica Verde; (ii) perfis verdes das práticas ministradas pelo Laboratório de Química Geral, do Departamento de Química da PUC-Rio, adotando-se ferramentas de avaliação usadas no campo da Química Analítica Verde, em nível mundial; (iii) indicação de práticas que poderão ser modificadas ou substituídas para atender aos princípios da Química Verde’aplicáveis, aos critérios definidos pelo Green Chemistry Institute e critérios complementares; (iv) conjunto de ações de Química Analítica Verde que poderão ser inseridas na Agenda Ambiental PUC-Rio.
The objective of this dissertation is to assess the potential of the Chemistry Department at PUC-Rio to develop and adopt Green Analytical Chemistry’s methods, within the perspective of contributing for the success of PUC-Rio’s Environmental Agenda. Within the institutional context in which this research is situated, it is assumed that its results will have a great potential for application in various departments of PUC-Rio, in particular in the Department of Chemistry. This research can be considered descriptive and applied and the methodology encompasses bibliographical and documental research, field research by mean of semi-structured interviews and case study. The main results can be summarized as follows: (i) survey of analytical methods that have been developed and used worldwide and have contributed to the advancement of Green Analytical Chemistry, (ii) green profiles of the laboratorial practices taught by General Chemistry Laboratory within the Chemistry Department at PUC-Rio; (iii) indication of laboratorial practices that can be improved or replaced by greener ones; (iv) a set of Green Analytical Chemistry’s actions to be considered in future revisions of PUC-Rio’s Environmental Agenda.

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23

Rosenthal-Kim, Emily Quinn. "Green Polymer Chemistry: Synthesis of Poly(disulfide) Polymers and Networks". University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1386525065.

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24

Zhang, Shiming. "Managing in conflict : how actors collaborate in marketing green chemistry". Thesis, University of Glasgow, 2016. http://theses.gla.ac.uk/7167/.

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The purpose of this research is to investigate business relationships, by drawing on conflict theories from organization studies and taking a mid-range research perspective to further develop these into industrial marketing research. IMP researchers have examined conflict as a threat to established business relationships and commercial exchanges, drawing on theories and concepts developed in organization studies. I adopt the behavioural approach from organisation studies, and contracts with particularly the socio-psychological approaches relating to the affective emotions of small groups. I find that there is much in common between the definitions of conflict developed by March (1999) and the theories of Jehn and Mannix (2001) on the combination of affective and cognitive ways of undertaking activities in conflicts, as conflict as experienced, emotional, aligned with material entities. These approaches have had a great influence but have not been fully considered in business-to-business research. This thesis aims to investigate how actors manage, and manage in, conflicts, and how their relationships dynamics work within networks. I develop conflict research by drawing on the IMP and Market Studies approaches, which address the pervasive conditions of business activity, encompassing the relationships and resources experienced by actors as events which trigger emotions. The overall research method chosen for this research is the case study. I identify five cases of relationships from the oil and gas industry’s service sector and examine conflict, its emotional dimensions and actors’ activities in conflicts within these cases in three empirical study chapters. Study 1 examines conflict of interest and resources and conflict as experienced by actors. Study 2 examines conflict from the emotional perspective by investigating a series of events and event-triggered emotions across the five cases of relationships. Study 3 focuses on adaptive activities undertaken in conditions of pervasive conflict, which produce incremental innovation. I propose an explanation of how actors manage, and manage in, conflict given that they tend to value and maintain relationships beyond individual episodes of exchange. Conflicts are investigated in relationships from a network perspective, showing that actors experienced these while adapting to changes in their business setting (regulation, technology or/and cost), modifying their roles in that network. By identifying conflict with the organizing forms of relationships and networks, the research shows how actors handle conflict by pursuing and combining a number of strategies, distributing the conflict across an enlarged network. By investigating the emotional dimension of conflicts, I find that affective emotion effects relationships and relationship dynamics. Actors transform and resource emotions with material entities, and in this process markets are shaped. Adaptations are part of the normal activities; actors, driven by medium term Chemical Management Service (CMS) contracts and cost pressures, undertake incremental innovation. An incremental innovation model is designed to illustrate the process of incremental innovation that operates for the ‘green chemical’ industry, and guides actors to contain costs through managing portfolios and resources, forecasting and innovation agenda, and reducing uncertainties in networks.

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25

Liao, Fenglin. "The development of Pd-based bimetallic nano-catalysts in green chemistry". Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:2fb03ce6-ba32-4102-96fc-f00fc7593bc0.

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With the gradual depletion of the non-renewable fossil fuel resources and the emerging environmental concerns, the need of exploring renewable synthesis routes of our daily basic stocks is rising. Due to the large contribution to the global primary energy (up to 40% in some countries), biomass has recently been advocated to be one of the most promising alternatives for fossil fuel. This thesis focuses on the catalytic transformations of biomass or biomass derived molecules into valuable small alcohols such as methanol, ethanol, and propanol, which can be used as both fuel and chemical synthesis intermediates. Novel catalysts with high activity and selectivity toward target products are desperately required in the development of renewable chemical synthesis routes. In the past 200 years, platinum metal catalysts have been widely used in the industry. But nowadays, Pd is attracting increasing attentions due to (i) its similar physicochemical properties to those of Pt, (ii) its higher natural abundance than Pt. Alloying has been demonstrated as an effective method in enhancing the catalytic properties of noble metals. In this thesis, a new and facile method for the preparation of supported bimetallic NPs with tunable compositions is developed. Through the establishment of a type II hetero-junction in support, controllable amounts of metallic atoms can be derived from the reduction of the metal oxide support, with the assistance of a supported noble metal. A series of extremely small Pd-based bimetallic NPs with a variety of modifier atoms at tunable compositions, namely PdFe, PdCo, PdNi and PdZn, have been synthesized by this method. These novel bimetallic NPs are applied to the catalytic conversion of biomass or biomass derived molecules containing repeating vicinal diol units. It is demonstrated that the catalytic performance of Pd in bimetallic phase is governed by the d-band structure. The high degree of d-band filling and high d-band center position favour the selective C-O cleavage in hydrogenolysis of vicinal diol units. On the other hand, the selective C-C cleavage can be achieved by lowering the d-band filling of the Pd-based bimetallic NPs. The specificity of C-C bond rupture over that of C-O increases in order of PdZn < PdNi < PdCo < PdFe, with progressive d-band filling reduction, eventually reaches 95% in a series of vicinal diols hydrogenolysis. As a result, small alcohols are produced with high selectivity as the degradation products of biomass molecules when PdFe bimetallic NPs are employed as catalyst. Conversely, by incorporating Co atoms at high concentration, PdCo exhibits a high selectivity in breaking C-O bond of ethylene glycol due to the raised d-band center position and gives ethanol as the main product. Pd@Zn bimetallic NPs with an imperfect core(Pd)-shell(Zn) structure were used in a methanol synthesis route from biomass transformation via CO₂ hydrogenation (CO₂/H₂ is produced from low temperature reforming of biomass resource). The Zn shell not only enhances the catalytic activity of Pd metal towards methanol synthesis, but also suppresses the reverse water gas shift (RWGS) reaction in which CO is produced as a by-product. Methanol can be produced as the main product over CO on the Zn rich Pd@Zn surface, even at low pressure. The methanol turnover frequency (TOF) on the exposed Pd site reaches 1.9 Ã10^-1 s^-1 with a selectivity of 70% at 2 MPa. The enhancement is attributed to the increasing d-band filling of Pd@Zn bimetallic NPs by the progressive decoration of Zn on Pd surface, which selectively stabilizes the precursor of methanol (HCOO) over that of CO (COOH). Also, the PdZn catalyst with high ability in dissociating H2 reduces the activation barrier for methanol synthesis. The results presented in this thesis, for the first time, signify the possibility of fine-tuning of product specificity of biomass conversion simply by rationally modifying the electronic properties of the Pd-based catalysts. More importantly, these catalysts will help to diversify the energy generation and relieve our dependence on fossil fuels.

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26

Posada, Pérez Sergio. "Heterogeneous catalysis of green chemistry reactions on molybdenum carbide based catalysts". Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/552405.

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Our society has a problem with the use of fossil fuels, due to the vast and exceeding emissions derived from human activities. Two ways could be consider to mitigate these harmful effects. On the one hand, the capture, activation, and conversion of these hazardous gases towards valuable compounds, and on the other hand, the substitution of fossil fuels for renewable energies. This thesis encompasses the study of two different green chemistry reactions to convert the most abundant greenhouse gas in Earth's atmosphere and the production of a new environmental friendly fuel, the hydrogen. In the current search for new catalysts, Transition Metal Carbides (TMCs) have arisen as an appealing alternative, because their exhibit broad and amazing physical and chemical properties and their low cost. In particular, titanium carbide (001) was proposed from experimental and theoretical points of view as active catalyst and support of small metal particles for CO2 hydrogenation to methanol and water gas shift reaction. However, given that titanium carbide is a cumbersome support to be used in applications due to the difficulty of obtaining nanoparticles on working conditions, we have carried out these reactions on cubic δ-MoC (001) and orthorhombic β-Mo2C (001) surfaces. The adsorption and activation of a CO2 molecule on cubic δ-MoC (001) and orthorhombic β-Mo2C (001) surfaces have been investigated by means of periodic density functional theory based calculations using the Perdew-Burke-Ernzerhof exchange-correlation functional showing that both surface are promising catalyst for CO2 conversion because they are able to activate and bend the CO2 molecule. The β- Mo2C (001) surface is able to dissociate the CO2 molecule easily, with a low energy barrier, whereas δ-MoC (001) surface activates CO2 but it does not promote its direct dissociation. Experiments accomplished by the group of Dr. Jose Rodriguez revealed that CO and methane are the main products of the CO2 hydrogenation using β-Mo2C (001) as catalyst, and the amount of methanol is lower. On the other hand, only CO and methanol are produced using δ-MoC (001). Experiments revealed that the deposition of small copper particles on the carbide surfaces increase drastically the catalysts' activity and selectivity, which was demonstrated by theoretical calculations. On β-Mo2C, the amount of CO and methanol increase whilst the amount of methane decrease, since copper blocks reactive sites on surface. This is a positive fact since copper avoid the excessive oxygen deposition, which deactivated the catalysts. On the other hand, the deposition of copper on δ-MoC (001) increases a lot the amount of CO and methanol. In summary, our combining DFT- experimental study proposed the Cu/δ-MoC as promising catalyst for CO2 hydrogenation due to its activity (the amount of products is superior than other TMCS, metals, and the model of commercial catalysts), selectivity (only CO and methanol are produced), and stability ( this catalysts is not deactivated by the oxygen deposition). The results obtained in the first part of the thesis were used to study the water gas shift reaction. Given that the excellent features, experiments proposed Au supported on δ-MoC (001) as catalysts. Our theoretical calculations demonstrated that clean δ-MoC (001) is not a good catalysts for WGS, due to the fact that the reverse reactions are favorable respect the direct ones, which implies that the amount of products is lower. Nevertheless, the deposition of Au clusters change the reaction mechanism, favoring the direct barriers instead of reverse ones, and increasing the amount of produced H2. In summary, this thesis has displayed the prominent role of molybdenum carbides as support of small metal particles to catalyze green chemistry reactions.
En aquesta tesi es mostra un treball computacional sobre l'ús de catalitzadors econòmics per a la conversió de CO2, un perillós gas d'efecte hivernacle i també per a la producció d'hidrogen, el combustible del futur. En la recerca actual de nous catalitzadors, els carburs de metalls de transició (TMC) han sorgit com una alternativa atractiva pel el seu baix cost i per exhibir excel·lents propietats físiques i químiques. En aquest treball utilitzarem com a catalitzadors les superfícies cúbica δ-MoC (001) i ortoròmbica β-Mo2C (001). L'adsorció de la molècula de CO2 mostra que ambdues superfícies són capaces d'activar i doblegar la molècula. La superfície β-Mo2C (001) és capaç de dissociar fàcilment la molècula de CO2, mentre que la superfície δ-MoC (001) activa CO2 però no la dissocia. Els experiments realitzats pel grup del Dr. Jose Rodriguez van revelar que el CO i el metà són els principals productes de la hidrogenació de CO2 utilitzant β-Mo2C (001) com a catalitzador, i la quantitat de metanol és menor. D'altra banda, només es produeixen CO i metanol utilitzant δ-MoC (001). La deposició de partícules de coure a les superfícies del carbur augmenta dràsticament l'activitat dels catalitzadors, cosa que es va demostrar mitjançant càlculs teòrics. A la superfície β-Mo2C, la quantitat de CO i metanol augmenten mentre que la quantitat de metà disminueix. D'altra banda, la deposició de coure a δ-MoC (001) augmenta molt la quantitat de CO i metanol. En resum, el nostre estudi proposa el Cu/δ-MoC com a prometedor catalitzador de la hidrogenació de CO2 a causa de la seva activitat (la quantitat de productes és superior a la resta de TMCS, metalls i el model de catalitzadors comercials), selectivitat (només el CO i el metanol es produeixen) i l'estabilitat (aquests catalitzadors no es desactiven per la deposició d'oxigen). Tenint en compte els resultats previs, es va proposar la deposició d'or en la superfície δ-MoC per a la producció d'hidrogen. Els càlculs teòrics demostren que la superfície δ-MoC (001) no és un bon catalitzador per WGS, però la deposició dels clústers d'or canvia el mecanisme de reacció i augmenta la quantitat d'H2 produïda.

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27

Matteo, Roberto <1985&gt. "Non-food Brassicas for green chemistry purposes through a biorefinery approach". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amsdottorato.unibo.it/8006/1/Matteo_Roberto_tesi.pdf.

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The valorization of Brassica oilseed crops, starting from the agronomical phase up to the exploitation of the derived products, was studied. Camelina sativa (L.) Crantz applications in biorefineries is of deep interest, given the high added value of its oil and oilseed cake residue. Camelina was evaluated as a case study for the cultivation in the Po valley. In such conditions, camelina has shown to be potentially well adaptable and had a positive impact on the yields of the subsequent crop. Thus, studies on camelina management and its impact on soil properties deserve more attention. Novel Brassica defatted seed meals (DSMs), containing different glucosinolates, were applied in the control of the southern root-knot nematode, Meloidogyne incognita (Kofoid & White Chitwood) in controlled glasshouse conditions. Among different Brassica DSMs, the best results in the reduction of M. incognita infestation were achieved by Eruca sativa, Barbarea verna and Brassica nigra DSMs. These first results open new perspectives for innovative bioactive molecules for biofumigation applied in cropping systems where nematode suppression is critical. Finally, the effect of Brassica DSMs, applied in formulations with and without crude glycerin, on seed germination inhibition was evaluated. The most effective formulations were applied in in vitro and glasshouse trials to evaluate the germination inhibition of black-grass (Alopecurus myosuriodes Huds.). Both in vitro and in vivo experiments confirmed the effectiveness of Brassica DSMs formulated with glycerin, especially B. nigra, in germination inhibition. Among different advantages, the proposed formulations for weed control are completely bio-based, organic farming friendly, present a good fertilizing properties and a combined effect both on weeds and on soil borne pests and diseases.

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28

Sachanandani, Rajiv M. Lombardo Stephen. "Failure analysis of green ceramic bodies during thermal debinding". Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6491.

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Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 18, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Thesis advisor: Dr. Stephen Lombardo. Includes bibliographical references.

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29

Sinha, Abhijeet Shekhar. "Constructing predictable supramolecular architectures using building blocks derived from versatile and ‘green’ synthetic routes". Diss., Kansas State University, 2013. http://hdl.handle.net/2097/16241.

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Doctor of Philosophy
Department of Chemistry
Christer B. Aakeröy
A series of four bifunctional ligands based on β-diketonate moieties bearing methyl, chloro, bromo and iodo substituents and their corresponding Cu(II) complexes were synthesized and crystallographically characterized in order to explore the possibility of using relatively weak halogen…halogen contacts for the directed assembly of predictable architectures in coordination chemistry. The four ligands have characteristic O–H...O intramolecular hydrogen bonds, and the structures of the halogenated ligands contain extended 1-D architectures based on C-O...X halogen bonds, which can be explained on the basis of electrostatic considerations. The corresponding Cu(II) complexes show a constant coordination chemistry for all the ligands, wherein the metal ion sits in a slightly distorted square-planar pocket, without any coordinated or uncoordinated solvent molecules. Furthermore, the absence of halogen-bonds in the coordination complexes is due to the depleted charge on the potential halogen-bond acceptors. As a result, the halogen-bonds are unable to compete with the inherent close packing in the crystal lattice, and thus display a head to head close-packed motif for methyl, chloro, and bromo, substituted Cu(II) complexes. The enhanced polarizability of the iodine atom, produces a more electropositive surface which means that this structure cannot accommodate a linear head-to-head arrangement due to electrostatic repulsion, and thus a unique close-packed structure very different from the three iso-structural complexes is observed for the iodo substituted Cu(II) complex.(1) Oximes offer great opportunities in supramolecular chemistry (hydrogen-bond donors), as well as in coordination chemistry (strong coordinating ligands). Hence, we established a versatile and robust mechanochemical route to aldehyde/ketone–oxime conversions for a broad range of aldehydes(2) and ketones(3) via a simple mortar–pestle grinding method. The relative reactivity of aldehydes vs. ketones under these conditions was also explored, along with an examination of the possible connection between reactivity and electronic substituent effects. The growing interest in the oxime (RR′C═N–OH) functionality, and a lack of the systematic examinations of the structural chemistry of such compounds, prompted us to carry out analysis of intermolecular oxime···oxime interactions, and identify the hydrogen-bond patterns for four major categories of oximes (R′ = −H, −CH3, −NH2, −CN), based on all available structural data in the CSD, complemented by three new relevant crystal structures.(4) It was found that the oximes could be divided into four groups depending on which type of predominant oxime···oxime interactions they present in the solid-state: (i) O–H···N dimers (R22(6)), (ii) O–H···N catemers (C(3)), (iii) O–H···O catemers (C(2)), and (iv) oximes in which the R′ group accepts a hydrogen bond from the oxime moiety catemers (C(6)). In order to explore and establish a hierarchy between hydrogen (HB) and halogen (XB) bonds in supramolecular architectures, we designed and synthesized two ditopic HB/XB donors, and screened them with a series of 20 HB acceptors. IR was used as a preliminary and reliable tool to gather information on the presence/absence of HB/XB in the different cases. We were able to get the solved single-crystal data for three of the 40 reactions. In two out of two cases with symmetric ditopic acceptors, both HB and XB were present leading to 1-D infinite chains, which suggests that in a system of “equal opportunities”, both these interactions can be tolerant of each other. In the only case with asymmetric ditopic acceptor, the HB donor binds to the best acceptor, whereas XB donor binds to the second best acceptor. This selectivity can be rationalized on the basis of electrostatic considerations, where the HB donor was shown to have a higher molecular electrostatic potential than the XB donor. Finally, we designed and synthesized a versatile and dynamic metallomacrocycle based on the 2,2'-bipyridyl backbone capable of controlling the metal-metal distance within the macrocycle cavity. The macrocycle was synthesized by high-dilution method and characterized by several spectroscopic techniques (IR, NMR, Mass, UV-Visible). Also, the macrocycle:Cu(II) stoichiometric ratio was determined by Job’s continuous variation method using UV-Visible spectroscopy, and was found to be 1:2, respectively. (1) Aakeröy, C. B; Sinha, A. S.; Chopade, P. D.; Desper, J. Dalton Trans. 2011, 40, 12160. (2) Aakeröy, C. B.; Sinha, A. S.; Epa, K. N.; Spartz, C. L.; Desper, J. Chem. Commun. 2012, 48, 11289. (3) Aakeröy, C. B.; Sinha, A. S. RSC Adv. 2013, 3, 8168. (4) Aakeröy, C. B.; Sinha, A. S.; Epa, K. N.; Chopade, P. D.; Smith, M. M.; Desper, J. Cryst. Growth Des. 2013, 13, 2687.

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30

Alghamdi, Reema M. "A SEM Study Of Copper Corrosion In Bowling Green Supply Lines". TopSCHOLAR®, 2015. http://digitalcommons.wku.edu/theses/1550.

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Recently, the rate of corrosion of copper water pipes in Bowling Green, Kentucky has unexpectedly accelerated. The specific reasons for this are unknown. Our aim is to elucidate the factors enhancing the corrosion and help understand the primary mechanisms of action. This will help in combating and reducing future corrosion incidents leading to pipe failure, thus reducing losses experienced when these pipes are replaced. This study seeks to explore the characteristics and factors involved. The scanning electron microscopy was used to obtain elemental composition, and images of both inside and outside of the corroded pipes. Strikingly, corrosion primarily occurred on the outside of the pipes, not inside. X-ray crystallography also was used to examine the pipes. The results showed that the interior of the pipes mostly consisted of SiO2, CuO2, CaCO3 while the exterior consisted of Cu2(OH)2CO3, Fe2Al2O4, CaCO3, SiO2 and Cu2O. There was no clear single factor for the corrosion observed. For further studies, we plan to long temporal experiments. The results from the study will help in minimizing the costs to the city in Bowling Green, Kentucky.

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31

Kherde, Yogesh A. "Green Synthesis and Evaluation of Catalytic Activity of Sugar Capped Gold Nanoparticles". TopSCHOLAR®, 2014. http://digitalcommons.wku.edu/theses/1388.

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Owing to the importance of gold nanoparticles in catalysis, designing of them has become a major focus of the researchers. Most of the current methods available for the synthesis of gold nanoaprticles (GNPs) suffer from the challenges of polydispersity, stability and use of toxic and harmful chemicals. To overcome these limitations of conventional methods, in our present study, we made an attempt to design a method for the green synthesis of monodispersed and stable gold nanoparticles by sugars which act as reducing and stabilizing agent. Characterization of synthesized nanoparticles was done by using various analytical techniques such as transmission electron microscope (TEM), dynamic light scattering spectroscopy (DLS), UV-Vis spectroscopy, scanning electron microscopy and electron dispersion spectroscopy. The synthesized sugar GNPs (S-GNPs) were spherical in shape and in the size range of 10 ± 5 nm. p-Nitrophenol reduction assay was used as a model system to determine the catalytic reduction activity of various sugar capped GNPs, monosaccharides (fructose), disaccharide (sucrose) and trisaccharide (raffinose) GNPs. The effect of temperature and the size of ligand on catalytic activity was also evaluated at different temperature using UV-Vis spectrometer. Using the spectroscopic data, rate constant (k) for three sugar capped GNPs was determined followed by its activation energy (Ea) and exponential (A) factor.

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32

Wang, Hansheng. "Electrochemical investigation of "green" film-forming corrosion inhibitors :". Thesis, KTH, Skolan för kemivetenskap (CHE), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-40888.

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In this work, a comparative electrochemical study has been performed to evaluate corrosion inhibition property of several film-forming corrosion inhibitors provide by Akzo Nobel on carbon steel in a chloride solution. For carbon steel exposed to 1 M NaCl solution with and without added inhibitor, electrochemical measurements including electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) at different exposure time intervals, and potentiodynamic polarization at the termination of the exposure, have been performed to investigate the film forming process and to evaluate corrosion inhibition efficiency of the inhibitors, as well as its evolution with time. The corrosion resistance data obtained from the EIS and LPR measurements are in good agreement. The results indicate different inhibition properties of the inhibitors tested. The inhibition effect of SSF CI-1 is negligible in the first hour of exposure, but it increases steadily with time for 1 day, and then remains the same level during the exposure up to one week. SSF CI-2 exhibits a good inhibition effect in the first hour, but the effect decreases with time to a low level after 8 hours, and then increases again with prolonged exposure. SSF CI-4 shows a low inhibition effect during the first day, and then increases to a maximum level after three days’ exposure. For SSF CI-5 and SSF CI-6, the inhibition effect within 8 hours is relative low but higher than that of SSF CI-4, and the effect increases with time during prolonged exposure. The SSF CI-5 seems to be better than SSF CI-6 because of a more stable inhibition effect. The EIS results indicate that most of the inhibitors form a resistive surface film on carbon steel, which becomes more resistive and protective after several days’ of exposure. However, in the initial stage of exposure, the SSF CI-6 does not show an effect of formation of a resistive film on the surface. The potentiodynamic polarization measurements suggest that, SSF CI-1 and SSF CI-2 are anodic type inhibitor, SSF CI-4 is cathodic type inhibitor, and SSF CI-5 and SSF CI-6 are mix type inhibitor. Moreover, the inhibitors tested show a similar corrosion inhibition effect as mussel adhesive protein (MAP) at the low dosage level.

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33

Balasubramanian, Narayanaganesh. "Stereoselective Carbon-Carbon Bond Construction Using Indium and Bismuth: New Methods in Green Chemistry". Diss., North Dakota State University, 2012. https://hdl.handle.net/10365/26531.

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Selective chemical reactions that can be accomplished with minimal waste using non-toxic catalysts and reagents will allow for new greener chemical processes for future environmentally sustainable technologies. This work will present an account on enantioselective nucleophilic addition to carbon-nitrogen and carbon-oxygen double bonds mediated by the environmentally benign indium and bismuth metals. The dissertation entitled “ Stereoselective carbon-carbon bond construction using indium and bismuth: new methods in green chemistry” is divided into three chapters Chapter one outlines a few concepts in green chemistry and background information on the vital role of indium and bismuth in present day organic synthesis. The development of a procedure for using allylic alcohol derivatives for ümpolung type allylation of chiral hydrazones is described in chapter two. This procedure affords homo allylic amines in good yields and excellent diastereoselectivity. An interesting study with respect to the mechanism of the reaction has been conducted. Switching gears towards the end of this chapter, ultrasound-promoted indium-mediated Reformatsky reaction of chiral hydrazones is described. This chapter describes a potential green chemical method for making β-amino acids. In chapter three, indium mediated enantioselective allylation of α-ketoamides is described. The developed procedure is applied in the allylation of linear and cyclic α- ketoamides. Overall, an operationally simple and environmentally benign stratergy development has been explained. The later section of this chapter discusses the Reformatsky reaction in isatin series using the same protocol applied for imines. To fully explore any organometallic reaction, it is important to understand the mechanism with which they operate at molecular level. Chapter three outlines some of our attempts to understand the enantioselective indium and bismuth mediated allylation and the nature of chiral- indium and bismuth Lewis acids. A postive non-linear effect has been observed and studied in bismuth-mediated allylation. Key findings obtained in each chapter and their implications to the future of our research is also discussed in each chapter. The chapters also details on what we understood about the potentials of organoindium and organobismuth chemistry towards developing new green chemical methods.

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34

Morigi, Francesca. "A green approach to mesoporous silica particles synthesis by sol-gel chemistry". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13434/.

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Mesoporous silica materials have a wide variety of applications in different sectors depending on their characteristic porosity, particle dimensions and functionalization. They are used as heterogeneous catalyst agents in industrial synthesis, stationary phase in chromatography or in biomedical applications as drug delivery systems. Consequently a significant number of studies have focused on the development of preparation methods that allow the regulation of the pore size and pore morphology of the silica. This thesis work, conducted at UCC (University College Cork, Ireland), aims to find a “greener” path than the one traditionally used to synthesize good quality mesoporous silica particles. It is a preliminary work whose purpose is to determine if it can be considered viable to start further systematic research in this direction. Nowadays it is impossible to ignore the need of an environmentally sustainable approach towards chemical synthesis and processes design. Green Chemistry and its Twelve Principles are central to the development of the mesoporous silica material preparation procedure utilized within this research. A modified Stöber sol-gel method of synthesis was chosen for its intrinsically green features: it is a batch process, the reaction takes place at room temperature and one of the main solvents is water. This study focuses on changing those aspects of the “standard” procedure which are not so environmentally friendly: the second solvent (alcohol), the surfactant (most commonly CTAB) and the post synthesis hydrothermal treatment. In particular Sodium Alginate, a polysaccharide extracted from the cell wall of brown seaweed, is the surfactant of choice. Until now no works have been reported on the use of alginate as a direct anionic surfactant template. Characterization of obtained silica particles was performed employing N2 sorption for information about porosity and SEM and TEM imaging to evaluate particles aggregation, aspect and size.

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35

Gómez, Núñez Alberto. "On the experimental and theoretical studies of ZnO precursors: towards Green Chemistry". Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/481979.

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Although an extensive number of investigators, during the arise of this printed materials technology, were devoted to make very interesting discoveries concerning the most used sol-gel precursor to thermally produce ZnO, the motives for which the ZnO material is formed in a certain way from some certain initial conditions is not yet well understood. The first effort carried out was to solve the crystal structure, never reported before, arising from the mixture between the zinc salt (Zinc acetate dihydrate) and the typical stabilizer used (Ethanolamine). This crystal structure was then compared with the molecular models designed and optimized by means of simulations. Simulationes were also useful in the study of the stability of this precursor and explaining the experimental results on its degradation in presence of light and CO2. Regarding the ZnO formation from the precursor’s thermal decomposition, it could be demonstrated the reason why the final ZnO was having traces of nitrogen at high temperatures. In addition, the theory regarding the specimens arising when the precursor is being degraded was also validated. Nevertheless, the presence of nitrogen at high temperatures as well as the toxic species that were evolving from the precursor when decomposing were a serious matter to confront. The aim of the next study was to investigate the substituent effects in this nitrogen-based ZnO precursor. To do so, up to seven aminoalcohols were used in order to study the dependence of rigidity on the stability and the decomposition process of the precursor. Experiments confirmed that the use of any of the aliphatic aminoalcohols in the precursor produce high stability comparing to those using aromatic aminoalcohols. They bolstered also the conclusion that the aminoalcohol’s rigidity plays and important role. It was additionally confirmed that the use of flexible aromatic stabilizers could be counterproductive, regarding the poor stability and the ZnO purity, while the aliphatic-based aminoalcohols provide better performances. Simulations were useful to comparatively study these different aminoalcohols in terms of stability and molecular dynamics at different temperatures. Dynamic simulations at different temperatures provided conclusive evidences on the nitrogen prevalence in the precursor even at high temperatures, suggesting that the Zn-N bond has effects on the thermal decomposition. For that reason, additives containing nitrogen are not the best solution to stabilize the metal and to produce pure ZnO (or at least with control on the contamination) at the same time. The next focused was on the desire to increase the number of Zn-O (weaker) interactions at the expense of eliminate the Zn-N bonds (stronger) using the so-popular Green Chemistry. Up to five ZnO precursors were synthesised following these principles, solving their crystal structure and studying their thermal decomposition. In order to increase the stability of the transition metal in the precursor, it was decided to resort to natural occurring carboxylic acids such as salicylic, citric, succinic and lactic acids. Thermal analysis found decomposition processes lasting ca. 150 C less than the required temperature for nitrogen-based precursors. Furthermore, these decomposition processes consisted of cleaner steps and purer ZnO with a lower temperature. Two of the five precursors were chosen, taking into account their delay in synthesizing and their solubility in common solvents (water and ethanol), to compare the behaviour of inks based on these precursors with the ones based on nitrogen compounds from the previous study. Continuous and homogeneous films of highly pure ZnO were obtained at lower temperatures adjusting the dwell time at the maximum temperature as well as the heating rate. At this point, there was only one proposal to make: the addition of new properties to those already existing in this ZnO. The addition of properties between two metals, well-known in Chemistry, is called molecular hybridization. Thus, the objective of this work was to synthesize an heteropolymetallic precursor that, through thermal decomposition, could generate the Franklinite / ZnO tandem with a variable iron content at will by controlling the atmosphere in which this precursor is decomposing.
La combinación de acetato de zinc y etanolamina conforma el precursor de sol-gel más utilizado para la producción de ZnO con fines de electrónica impresa. Aunque las propiedades de tinta basadas en precursores se han reportado ampliamente, las razones por las que el material de ZnO se forma de cierta manera a partir de condiciones iniciales específicas todavía no se conocen bien. En el presente trabajo, la estructura de la mezcla se caracteriza experimentalmente y se compara con los modelos moleculares optimizados mediante simulaciones. Además, se ha demostrado tanto los procesos que llevan a su degradación a temperatura ambiente como la descripción del proceso de descomposición indica efectos de sustituyentes importantes en este precursor basado en nitrógeno, que se analizan mejor comparando varios amino-alcoholes con diferentes sustituciones de radicales. La falta de control sobre los efectos de estos amino-alcoholes en el material final hace deseable aumentar el número de interacciones Zn-O (más débiles) a expensas de eliminar los enlaces Zn-N (más intensos). En consecuencia, se han diseñado nuevos precursores sobre la base de la Química verde recurriendo para ello a ácidos carboxílicos naturales. Se describen aquí sus estructuras cristalinas y procesos de descomposición térmica, que consisten en pasos más limpios y en la producción de un ZnO más puro a temperaturas más bajas que cuando se usan amino-alcoholes para estabilizar el metal Zn (II). Al agregar solventes comunes (agua y etanol), las tintas obtenidas muestran claras mejoras para las tecnologías de impresión basadas en precursores de ZnO. Como último estudio, se procedió a la incorporación de un segundo metal en este tipo de precursores, el hierro, con el fin de estudiar la conveniencia en la disposición de dos metales que, en función de la atmosfera en la que se descomponga el precursor, generen una proporción controlada de Franklinita (conocida por sus propiedades magnéticas) con respecto a la proporción de ZnO. Un estudio futuro más detallado sobre esta Franklinita podría, incluso, detallar las condiciones en las que encontrar la proporción de Fe(II)/Fe(III), y por tanto su capacidad magnética, deseada para cada fin.

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36

Demirci, Sema. "Synthesis Of Heteroaryl Substituted Dihydrofuran And Dihydropyran Derivatives By Green Chemistry Approach". Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610966/index.pdf.

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The thesis subject is mainly involved in Green Chemistry approach. Thiophene, furan and pyridine carboxaldehydes were chosen as starting compounds and vinylation and allylation with Grignard reaction afforded the corresponding racemic heteroaryl substituted allylic and homoallylic alcohols. Subsequent resolution with enzymes (PS-Amano II, Lipozym and Novazym 435) gave enantiomerically enriched alcohols with the e.e. values varied between 65 and 99%. The absolute configurations of all substrates are known. As a result of O-allylation with the common procedure formed the feasible carbon backbone for the ring closing metathesis reaction. All ring closing metathesis reactions were performed by Grubbs&rsquo
catalyst with just 5% catalyst loading. The absolute configurations of dihydrofuran and dihydropyran derivatives are known, since the chiral center configurations of all substrates are preserved throughout all the applied processes.

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37

Allen, Andrew J. (Andrew John) 1978. "Green chemistry : dense carbon dioxide and water as environmentally benign reaction media". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28656.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2004.
Includes bibliographical references.
(cont.) was investigated in scCO₂, and the cycloaddition between cyclopentadiene and methyl vinyl ketone (MVK) was studied in an scCO₂/liquid water environment. Nitrogen chemistry, specifically the synthesis of nitrogen heterocycles from amines, was also studied in scCO₂ and scCO₂/liquid water systems. The objective of studying the Diels-Alder cycloaddition of 9-hydroxymethylanthracene with N-ethylmaleimide in scCO₂ was to demonstrate the ability of scCO₂ to dramatically accelerate the rate of this reaction when compared to conventional solvents. Using spectroscopy to track the disappearance of the 9-hydroxymethylanthracene peak, it was found that this reaction proceeds at rates in scCO₂ that are significantly faster than in traditional organic solvents. It was also observed that the reaction rate constant increased with decreasing density, opposite the trend normally observed for most reactions conducted in scCO₂. On the basis of the low solubility of 9-hydroxymethylanthracene in scCO₂ and similar results observed in fluorocarbon solvents (fluorocarbons and scCO₂ are known to behave similarly as solvents), a solvophobic mechanism was inferred as the cause of the rate acceleration observed for this particular reaction in scCO₂. In order to utilize the complementary solvation powers of scCO₂ and water, a second Diels-Alder reaction, cyclopentadiene with MVK, was studied in an scCO₂/liquid water mixture. Specifically, the effect of MVK concentration on the selectivity and conversion was studied under both silent and sonicated conditions ...
With an ever increasing focus on reducing the environmental impact of solvent releases on human health and the environment, the replacement of conventional, organic solvents with alternative compounds that are inherently benign has attracted much attention in both industry and academia. Supercritical carbon dioxide (scCO₂) and water are two alternative compounds that are of particular interest because they are non-toxic, non-flammable, readily available, and cheap. Although scCO₂ has been successfully used in industry as a solvent for selective extraction (e.g. extraction of caffeine from coffee beans), development of scCO₂ as a reaction solvent has been less successful due to its limited solvation power for many organic reagents of interest. In addition scCO₂ has generally been shown to reduce both the reaction rate and selectivity of many reactions when compared to conventional solvents. Unlike scCO₂, water is known to significantly accelerate reaction rates and improve selectivities over that obtainable in conventional solvents. However, most organic compounds are insoluble in water which has limited its use as a reaction solvent for industrial-scale processes. In order to replace conventional solvents with scCO₂ and/or water, significant technological advantages resulting from the use of these compounds will have to be demonstrated. This research attempts to demonstrate some potential advantages of using scCO₂ and scCO₂/water as reaction media for several synthetic transformations of interest. The Diels-Alder cycloaddition of 9-hydroxymethylanthracene and N-ethylmaleimide
by Andrew J. Allen.
S.M.

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38

Hamdi, Meshal. "E-Waste Recycling System for Computers and Mobile Devices Using Green Chemistry". Digital Commons at Loyola Marymount University and Loyola Law School, 2015. https://digitalcommons.lmu.edu/etd/390.

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39

Samorì, Chiara <1982&gt. "Use of solvents and environmental friendly materials for applications in Green Chemistry". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2840/1/Samori_Chiara_tesi.pdf.

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The present Thesis studies three alternative solvent groups as sustainable replacement of traditional organic solvents. Some aspects of fluorinated solvents, supercritical fluids and ionic liquids, have been analysed with a critical approach and their effective “greenness” has been evaluated from the points of view of the synthesis, the properties and the applications. In particular, the attention has been put on the environmental and human health issues, evaluating the eco-toxicity, the toxicity and the persistence, to underline that applicability and sustainability are subjects with equal importance. The “green” features of fluorous solvents and supercritical fluids are almost well-established; in particular supercritical carbon dioxide (scCO2) is probably the “greenest” solvent among the alternative solvent systems developed in the last years, enabling to combine numerous advantages both from the point of view of industrial/technological applications and eco-compatibility. In the Thesis the analysis of these two classes of alternative solvents has been mainly focused on their applicability, rather than the evaluation of their environmental impact. Specifically they have been evaluated as alternative media for non-aqueous biocatalysis. For this purpose, the hydrophobic ion pairing (HIP), which allows solubilising enzymes in apolar solvents by an ion pairing between the protein and a surfactant, has been investigated as effective enzymatic derivatisation technique to improve the catalytic activity under homogeneous conditions in non conventional media. The results showed that the complex enzyme-surfactant was much more active both in fluorous solvents and in supercritical carbon dioxide than the native form of the enzyme. Ionic liquids, especially imidazolium salts, have been proposed some years ago as “fully green” alternative solvents; however this epithet does not take into account several “brown” aspects such as their synthesis from petro-chemical starting materials, their considerable eco-toxicity, toxicity and resistance to biodegradation, and the difficulty of clearly outline applications in which ionic liquids are really more advantageous than traditional solvents. For all of these reasons in this Thesis a critical analysis of ionic liquids has been focused on three main topics: i) alternative synthesis by introducing structural moieties which could reduce the toxicity of the most known liquid salts, and by using starting materials from renewable resources; ii) on the evaluation of their environmental impact through eco-toxicological tests (Daphnia magna and Vibrio fischeri acute toxicity tests, and algal growth inhibition), toxicity tests (MTT test, AChE inhibition and LDH release tests) and fate and rate of aerobic biodegradation in soil and water; iii) and on the demonstration of their effectiveness as reaction media in organo-catalysis and as extractive solvents in the recovery of vegetable oil from terrestrial and aquatic biomass. The results about eco-toxicity tests with Daphnia magna, Vibrio fischeri and algae, and toxicity assay using cultured cell lines, clearly indicate that the difference in toxicity between alkyl and oxygenated cations relies in differences of polarity, according to the general trend of decreasing toxicity by decreasing the lipophilicity. Independently by the biological approach in fact, all the results are in agreement, showing a lower toxicity for compounds with oxygenated lateral chains than for those having purely alkyl lateral chains. These findings indicate that an appropriate choice of cation and anion structures is important not only to design the IL with improved and suitable chemico-physical properties but also to obtain safer and eco-friendly ILs. Moreover there is a clear indication that the composition of the abiotic environment has to be taken into account when the toxicity of ILs in various biological test systems is analysed, because, for example, the data reported in the Thesis indicate a significant influence of salinity variations on algal toxicity. Aerobic biodegradation of four imidazolium ionic liquids, two alkylated and two oxygenated, in soil was evaluated for the first time. Alkyl ionic liquids were shown to be biodegradable over the 6 months test period, and in contrast no significant mineralisation was observed with oxygenated derivatives. A different result was observed in the aerobic biodegradation of alkylated and oxygenated pyridinium ionic liquids in water because all the ionic liquids were almost completely degraded after 10 days, independently by the number of oxygen in the lateral chain of the cation. The synthesis of new ionic liquids by using renewable feedstock as starting materials, has been developed through the synthesis of furan-based ion pairs from furfural. The new ammonium salts were synthesised in very good yields, good purity of the products and wide versatility, combining low melting points with high decomposition temperatures and reduced viscosities. Regarding the possible applications as surfactants and biocides, furan-based salts could be a valuable alternative to benzyltributylammonium salts and benzalkonium chloride that are produced from non-renewable resources. A new procedure for the allylation of ketones and aldehydes with tetraallyltin in ionic liquids was developed. The reaction afforded high yields both in sulfonate-containing ILs and in ILs without sulfonate upon addition of a small amount of sulfonic acid. The checked reaction resulted in peculiar chemoselectivity favouring aliphatic substrates towards aromatic ketones and good stereoselectivity in the allylation of levoglucosenone. Finally ILs-based systems could be easily and successfully recycled, making the described procedure environmentally benign. The potential role of switchable polarity solvents as a green technology for the extraction of vegetable oil from terrestrial and aquatic biomass has been investigated. The extraction efficiency of terrestrial biomass rich in triacylglycerols, as soy bean flakes and sunflower seeds, was comparable to those of traditional organic solvents, being the yield of vegetable oils recovery very similar. Switchable polarity solvents as been also exploited for the first time in the extraction of hydrocarbons from the microalga Botryococcus braunii, demonstrating the efficiency of the process for the extraction of both dried microalgal biomass and directly of the aqueous growth medium. The switchable polarity solvents exhibited better extraction efficiency than conventional solvents, both with dried and liquid samples. This is an important issue considering that the harvest and the dewatering of algal biomass have a large impact on overall costs and energy balance.

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40

Samorì, Chiara <1982&gt. "Use of solvents and environmental friendly materials for applications in Green Chemistry". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amsdottorato.unibo.it/2840/.

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The present Thesis studies three alternative solvent groups as sustainable replacement of traditional organic solvents. Some aspects of fluorinated solvents, supercritical fluids and ionic liquids, have been analysed with a critical approach and their effective “greenness” has been evaluated from the points of view of the synthesis, the properties and the applications. In particular, the attention has been put on the environmental and human health issues, evaluating the eco-toxicity, the toxicity and the persistence, to underline that applicability and sustainability are subjects with equal importance. The “green” features of fluorous solvents and supercritical fluids are almost well-established; in particular supercritical carbon dioxide (scCO2) is probably the “greenest” solvent among the alternative solvent systems developed in the last years, enabling to combine numerous advantages both from the point of view of industrial/technological applications and eco-compatibility. In the Thesis the analysis of these two classes of alternative solvents has been mainly focused on their applicability, rather than the evaluation of their environmental impact. Specifically they have been evaluated as alternative media for non-aqueous biocatalysis. For this purpose, the hydrophobic ion pairing (HIP), which allows solubilising enzymes in apolar solvents by an ion pairing between the protein and a surfactant, has been investigated as effective enzymatic derivatisation technique to improve the catalytic activity under homogeneous conditions in non conventional media. The results showed that the complex enzyme-surfactant was much more active both in fluorous solvents and in supercritical carbon dioxide than the native form of the enzyme. Ionic liquids, especially imidazolium salts, have been proposed some years ago as “fully green” alternative solvents; however this epithet does not take into account several “brown” aspects such as their synthesis from petro-chemical starting materials, their considerable eco-toxicity, toxicity and resistance to biodegradation, and the difficulty of clearly outline applications in which ionic liquids are really more advantageous than traditional solvents. For all of these reasons in this Thesis a critical analysis of ionic liquids has been focused on three main topics: i) alternative synthesis by introducing structural moieties which could reduce the toxicity of the most known liquid salts, and by using starting materials from renewable resources; ii) on the evaluation of their environmental impact through eco-toxicological tests (Daphnia magna and Vibrio fischeri acute toxicity tests, and algal growth inhibition), toxicity tests (MTT test, AChE inhibition and LDH release tests) and fate and rate of aerobic biodegradation in soil and water; iii) and on the demonstration of their effectiveness as reaction media in organo-catalysis and as extractive solvents in the recovery of vegetable oil from terrestrial and aquatic biomass. The results about eco-toxicity tests with Daphnia magna, Vibrio fischeri and algae, and toxicity assay using cultured cell lines, clearly indicate that the difference in toxicity between alkyl and oxygenated cations relies in differences of polarity, according to the general trend of decreasing toxicity by decreasing the lipophilicity. Independently by the biological approach in fact, all the results are in agreement, showing a lower toxicity for compounds with oxygenated lateral chains than for those having purely alkyl lateral chains. These findings indicate that an appropriate choice of cation and anion structures is important not only to design the IL with improved and suitable chemico-physical properties but also to obtain safer and eco-friendly ILs. Moreover there is a clear indication that the composition of the abiotic environment has to be taken into account when the toxicity of ILs in various biological test systems is analysed, because, for example, the data reported in the Thesis indicate a significant influence of salinity variations on algal toxicity. Aerobic biodegradation of four imidazolium ionic liquids, two alkylated and two oxygenated, in soil was evaluated for the first time. Alkyl ionic liquids were shown to be biodegradable over the 6 months test period, and in contrast no significant mineralisation was observed with oxygenated derivatives. A different result was observed in the aerobic biodegradation of alkylated and oxygenated pyridinium ionic liquids in water because all the ionic liquids were almost completely degraded after 10 days, independently by the number of oxygen in the lateral chain of the cation. The synthesis of new ionic liquids by using renewable feedstock as starting materials, has been developed through the synthesis of furan-based ion pairs from furfural. The new ammonium salts were synthesised in very good yields, good purity of the products and wide versatility, combining low melting points with high decomposition temperatures and reduced viscosities. Regarding the possible applications as surfactants and biocides, furan-based salts could be a valuable alternative to benzyltributylammonium salts and benzalkonium chloride that are produced from non-renewable resources. A new procedure for the allylation of ketones and aldehydes with tetraallyltin in ionic liquids was developed. The reaction afforded high yields both in sulfonate-containing ILs and in ILs without sulfonate upon addition of a small amount of sulfonic acid. The checked reaction resulted in peculiar chemoselectivity favouring aliphatic substrates towards aromatic ketones and good stereoselectivity in the allylation of levoglucosenone. Finally ILs-based systems could be easily and successfully recycled, making the described procedure environmentally benign. The potential role of switchable polarity solvents as a green technology for the extraction of vegetable oil from terrestrial and aquatic biomass has been investigated. The extraction efficiency of terrestrial biomass rich in triacylglycerols, as soy bean flakes and sunflower seeds, was comparable to those of traditional organic solvents, being the yield of vegetable oils recovery very similar. Switchable polarity solvents as been also exploited for the first time in the extraction of hydrocarbons from the microalga Botryococcus braunii, demonstrating the efficiency of the process for the extraction of both dried microalgal biomass and directly of the aqueous growth medium. The switchable polarity solvents exhibited better extraction efficiency than conventional solvents, both with dried and liquid samples. This is an important issue considering that the harvest and the dewatering of algal biomass have a large impact on overall costs and energy balance.

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41

Granville, Stephanie L. "Studies of Iron Polyfluorometallacycle Complexes Enroute to the "Green" Catalytic Synthesis of Hydrofluorocarbons". Thesis, University of Ottawa (Canada), 2011. http://hdl.handle.net/10393/28894.

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Chlorofluorocarbons were once commonly used as propellants and refrigerants due to their stability, low toxicity and excellent physical properties. They were phased out, however, after being identified as ozone-depleters, and have been replaced by hydrofluorocarbons (HFCs) and other fluorocarbon derivatives (FCDs). The high temperature-resistant characteristic of these materials is beneficial for many applications; however, the robust nature of the C-F bonds leads to their persistence in the environment. Frequently, the synthesis of HFCs and FCDs involves energy-intensive processes and toxic precursors, such as chlorocarbons and heavy metals. In accordance with the shift to greener, more sustainable chemistry, more energy efficient methods employing less hazardous and non-toxic materials for the generation of HFCs and FCDs need to be developed. Organometallic catalysis offers potential new routes to the synthesis of fluorinated compounds. We sought to study the reactivity of tetrafluoroethylene and 1,1-difluoroethylene with a variety of iron complexes to increase our understanding of the bonding and chemistry of coordinated fluoro-olefins. Crystal structures were obtained for the parent and dppe substituted metallaycles: Fe(CF2) 4(CO)4 and Fe(CF2)4(K2-dppe)(CO) 2. Sterics were found to be responsible for the preferential formation of three- versus five-membered metallacycles through investigating the reactivity of TFE with iron phosphine- and phosphite-carbonyl complexes, as well as with the homoleptic complex pentakis(2,6-dimethylphenylisocyanide)iron and the anionic complex K[FeCp(CO)2]. The five-membered metallacycle was selectively formed with the mono-substituted phosphine and phosphite complexes, whereas, the di-substituted complexes yield the olefin (three-membered metallacycle) complexes. With the goal of developing methods for iron-mediated fluoride abstraction, the reactivity of these iron fluoro-metallacycles with a variety of Lewis acids was probed. Extremely electrophillic fluoro-carbenes were generated. A more electron rich metal centre, as in the thermally synthesized K[FeCp(CF 2)4(CO)2], is required to facilitate fluoride abstraction and stabilize the fluor-ocarbene. The results that were obtained in this investigation set the stage well for further development of iron-based organofluorometallic chemistry and our desire to functionalize the alpha-carbon of the metallacycle enroute to the generation of novel FCs.

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42

Shorrock, Jennifer Kate. "Cationic polymerisation of alicene monomers by silica-supported aluminium chloride". Thesis, University of York, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250624.

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43

Beltrán, Suito Rodrigo. "Surprisingly green: copper and its pigments". Revista de Química, 2013. http://repositorio.pucp.edu.pe/index/handle/123456789/99887.

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El premio Ig Nobel de Química 2012 fue otorgado al ingeniero sueco Johan Petterson por explicar que el cobre era el responsable de teñir el cabello de verde a los habitantes de una pequeña población sueca. En la naturaleza existen numerosos compuestos verdes de cobre, que se usan como pigmentos, y está presente también en las hemocianinas, enzimas sanguíneas de algunos artrópodos y moluscos.
The 2012 Ig Nobel Prize in Chemistry was awarded to Johan Petterson, a Swedish engineer who discovered that copper was responsible for turning hair green in a little Swedish town. Many green copper compounds used as pigments are present in nature and there are also the hemocyanins, copper-containing proteins found in the blood of some arthropods and mollusks.

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44

Bertolucci, Elisa. "Green Synthesis of magnetic nanostructures suitable as recoverable nanocatalysts and conductive nanomaterials". Doctoral thesis, Scuola Normale Superiore, 2016. http://hdl.handle.net/11384/86197.

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45

Alessio, Caretto. "Green transformations of bio-based chemicals". Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/12727.

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The thesis was focused on the development of green chemical technologies for the upgrading of platform molecules obtainable from renewable feedstocks. The platforms were chosen among those considered as the most promising for the development a new, sustainable, chemical industry. Levulinic acid was converted into compounds with a higher degree of oxygenation without actually using oxidizing agents. This was achieved by using dimehtyl carbonate (DMC), a green reagent and solvent, in basic catalysis. Bio-derived lactones (γ-valero-, γ-butyro-, δ-valero- and ε-capro-lactone) were reacted with three dialkylcarbonates (DMC, diethyl- and dibenzylcarbonate) to yield α-alkylated derivatives (from the 5-membered rings) or the highly oxygenated acyclic monomeric derivatives (from 6- and 7-membered rings). γ-valerolactone was used as a model to study acid catalysed ring-opening reactions. A novel reactivity was discovered in the presence of DMC; a mechanism was proposed. The 4-methoxy pentanoyl moiety was thus accessible by a green route. The reaction was then extended to a continuous flow process with solid acid catalysts. The selectivity towards the mentioned moiety or methyl pentenoate was tuned by optimising the parameters. Bio-derived diols were efficiently upgraded using organic carbonates in tandem with ionic liquids as organocatalysts. The study investigated the parameters that control the selectivity towards cyclic- or linear di-carbonates. The derivatisation of fatty acids methyl esters in conditions of on-water catalysis was investigated, aiming to develop a green strategy to reduce the cloud point of biodiesels. A new branched additive was synthesised, the thermal characteristics of which were analysed. The effect of reagents structure on on-water catalysis was investigated. The model reactions between cyclopentadiene and alkyl vinyl ketones allowed to demonstrate that little increases of the alkyl chain of a reactant have a dramatic influence on the catalytic effect.

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46

Marus, Gregory Alan. "The application of green chemistry and engineering to novel sustainable solvents and processes". Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/43755.

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The implementation of sustainable solvents and processes is critical to new developments in reducing environmental impact, improving net efficiency, and securing economic profitability in the chemical and pharmaceutical industries. In order to address the challenge of sustainability, researchers have used switchable solvents for both reaction and separation by utilizing a built-in switch to undergo a step change in chemical and physical properties. This allows us to facilitate reactions in the solvent then activate the switch to enable separation and facile product recovery. Subsequently, we can recover the solvent for reuse and avoid energy- or waste-intensive separation processes; thus we are developing and using these switchable solvents as sustainable and environmentally benign alternatives to traditional processes. In this research, we enable the sustainable scale-up of a switchable solvent - piperylene sulfone - a "volatile" and recyclable DMSO replacement. In the development of this process, we improved the reaction performances and developed a green purification method. Furthermore, we enable and demonstrate the implementation of a Meerwein-Ponndorf-Verley (MPV) reduction, a pharmaceutically relevant reaction, into a continuous flow platform. The innovation of continuous flow processes can replace traditional batch reaction technology, and is indeed a key research area that has been acknowledged by the pharmaceutical industry. Additionally, we utilize the switchable sulfone solvents, piperylene and butadiene sulfone, for reaction and separation of HMF produced from monosaccharides as an alternative to a process which has been limited by an inefficient separation step.

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47

Castano, Gil Yenni Marcela. "Green Polymer Chemistry: The Role of Candida Antarctica Lipase B in Polymer Functionalization". University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1398034236.

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48

Corno, L. "ARUNDO DONAX L. (GIANT CANE) AS A FEEDSTOCK FOR BIOENERGY AND GREEN CHEMISTRY". Doctoral thesis, Università degli Studi di Milano, 2016. http://hdl.handle.net/2434/347217.

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Arundo donax L. or giant cane is a second-generation energy crop that could be used as a feedstock for bioenergy, i.e. biogas, bioethanol, combustion, and in green chemistry as raw material for several industrial sectors. The genetic characterization of A. donax plants revealed that, because of its asexual reproduction, low genetic variability could be detected between plants; the studies on the inflorescences also confirmed the agamic reproduction of the plant. Nevertheless, it could be speculated that some genetic characteristics could be hereditable and a selection of clones could be carried out. The clonal selection showed to be a crucial factor also for the choice of the propagation techniques and their final costs. A. donax biomass conservation by ensilage was possible without using inoculum. The preservation of giant cane could be performed by the two most used silage techniques, trench and silo-bag; the silo-bag technique was more efficient in preserving the biogas potential than trench one. The potential biogas production of A. donax silage in comparison to corn silage was tested by simulation of real-scale anaerobic digestion plant with lab-scale trials. The A. donax biogas production was lower than the one obtained with corn due to the chemical characteristics of biomass and the absence of starch but, thanks to the higher biomass yields, achievable biomethane and electric energy referred to the cultivated surface area were much higher than corn and other traditional energy crops.

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49

Shah, Monic. "Antimicrobial Nanoparticles: A Green and Novel Approach for Enhancing Bactericidal Efficacy of Commercial Antibiotics". TopSCHOLAR®, 2014. http://digitalcommons.wku.edu/theses/1389.

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On the verge of entering the post-antibiotic era, numerous efforts are in place to regain the waning charm of antibiotics which are proving ineffective against most “Superbugs”. Engineered nanomaterials, especially gold nanoparticles (GNPs) capped with antibacterial agents, are proving to be an effective and novel strategy against multidrug resistant (MDR) bacteria. In this study, we report a one-step synthesis of antibioticcapped GNPs (25 ± 5 nm) utilizing the combined reducing and capping ability of a cephalosporin antibiotic, ceftazidime. No signs of aggregation or leaching of ceftazidime from GNP surface was observed upon its storage. Antibacterial testing showed dosedependent broad spectrum activity of Cef-GNPs against both Gram-positive (S. bovis and E. durans) and Gram-negative (P. aeruginosa and E. aerogenes) bacteria. A significant reduction in the minimum inhibition concentration (MIC) of Cef-GNPs was observed as compared to the ceftazidime by itself against Gram-negative bacteria. The MIC of Cef- GNPs were 0.1 mg mL-1 (P. aeruginosa and E. aerogenes) and 1.2 mg mL-1 (E. durans and S. bovis). Cef-GNPs exerted bactericidal action on both P. aeruginosa and E. durans by disrupting the cellular membrane resulting in leakage of cytoplasmic content and death of bacterial cell. Our investigation and results provides an additional step in the development of antibiotic capped GNP as potent next generation antibacterial agents.

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50

Bunch, Nathan. "Oral Fluid Method Validation for Bowling Green State University". Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1586969951770212.

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