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Makgae, Mosidi Elizabeth. "Environmental electrochemistry of organic compounds at metal oxide electrodes." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/49947.
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Dissertation (PhD)--Stellenbosch University, 2004.ENGLISH ABSTRACT: This study investigates the electrochemical oxidation of phenol. Phenol is a major toxin and water pollutant. In addition, during water treatment it reacts with chlorine to produce carcinogenic chlorophenols. lts treatment down to trace levels is therefore of increasing concern. For this purpose, dynamically stable anodes for the breakdown of phenols to carbon dioxide or other less harmful substances were developed and characterized. The anodes were prepared from mixed oxides of tin (Sn) and the precious metals ruthenium (Ru), tantalum (Ta) and iridium (Ir), which in tum were prepared using sol-gel techniques. This involved dip-coating the aqueous salts of the respective metals onto titanium substrates and heating to temperatures of several hundreds of degree Celsius. The properties of these mixed oxide thin films were investigated and characterized using thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), atomic force microscopy (AFM), elemental dispersive energy X-ray analysis (EDX), X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS), particle induced X-ray emission (PIXE) and electrochemical measurements. A variety of different electrode materials including Til Sn02-Ru02-Ir02, Ti/Ta20s-Ir02 and Ti/RhOx-Ir02 were developed and tested for their potential as oxidation catalysts for organic pollutants in wastewaters. Depending on the anode type, phenol was found to be electrochemically degraded, to different extents, on these surfaces during electrolysis. It was however found that the oxidation rate not only depended on the chemical composition but also on the oxide morphology revealed, resulting from the preparation procedure. The Ti/SnOz-Ru02-Ir02 film was found to be the most efficient surface for the electrolytic breakdown of phenol. This film oxidized phenol at a potential of 200 mV vs Ag/AgC!. The activity of the catalytic systems was evaluated both on the basis of phenol removal efficiency as well as the kinetics of these reactions. Phenol removal efficiency was more than 90% for all the film surfaces prepared and the rate of the reaction followed first order kinetics. A pathway for the electrochemical degradation of phenol was derived using techniques such as HPLC to identify the breakdown products. These pathway products included the formation of benzoquinone and the further oxidation of benzoquinone to the carboxylic acids malic, malonic and oxalic.
AFRIKAANSE OPSOMMING: Die onderwerp van hierdie studie is die elektrochemiese oksidasie van fenol deur nuwe gemengde-oksied elektrodes. Fenol is 'n belangrike gifstof en besoedelingsmiddel in water. Daarbenewens kan fenolook met chloor reageer tydens waterbehandeling om sodoende karsinogeniese chlorofenole te vorm. Dit is dus belangrik dat metodes ondersoek word wat die konsentrasie van fenol in water verminder. Hierdie studie behels die bereiding en karakterisering van nuwe dinamiese stabiele anodes (DSA) vir die afbreek van fenol tot koolstofdioksied en ander minder gevaarlike verbindings. Hierdie nuwe anodes is berei vanaf die gemengde-okside van die edelmetale tin (Sn), ruthenium (Ru), tantalum (Ta) en iridium (Ir), met behulp van sol-gel tegnieke. Die finale stap in die bereiding behels kalsinering van die oksides by temperature van "n paar honderd grade Celsius. Hierdie nuwe elektrodes is later gebruik om die oksidasie van fenol te evalueer. Die gemengde-oksied dunlae/anodes IS d.m.v. die volgende analitiesetegnieke gekarakteriseer: termiese-gravimetriese analise (TGA), skandeerelektronmikroskopie (SEM), atoomkragmikroskopie (AFM), elementverstrooiingsenergie- X-straalanalise (EDX), X-straaldiffraksie (XRD), Rutherford terug-verstrooiingspektroskopie (RBS), partikel-geinduseerde X-straal emissie (PIXE), en elektrochemiese metings. 'n Verskeidenheid elektrodes van verskillende materiale is berei en hul potensiaal as oksidasie-kataliste vir organiese besoedelingsmiddels in afloopwater bepaal. Hierdie elektrodes het die volgende ingesluit: Ti/Sn02-Ru02-Ir02, Ti/Ta20s-Ir02 en Ti/RhOx-Ir02. Gedurende elektrolise is fenol elektrochemies afgebreek tot verskillende vlakke, afhangende van die tipe elektrode. Die oksidasietempo het egter nie alleen van die chemiese samestelling van die elektrode afgehang nie, maar ook van die morfologie van die okside, wat op hulle beurt van die voorbereidingsprosedure afgehang het. Daar is bevind dat die Ti/Sn02-Ru02-Ir02 elektrode die mees effektiewe oppervlakke vir die afbreek van fenol is. Hier het die oksidasie van fenol by 'n potensiaal van 200 mV plaasgevind. Die aktiwiteite van die katalitiese sisteme IS bepaal op grond van hulle fenolverwyderingsdoeltreffendheid. Die kinetika van die reaksies is ook bepaal. Al die elektrodes het >90% fenolverwyderingsdoeltreffendheid getoon en die reaksietempos was van die eerste-orde. Deur van analitiese tegnieke soos hoëdrukvloeistofchromatografie (HPLC) gebruik te maak is die afbreekprodukte van fenol geïdentifiseer en 'n skema vir die elektrochemiese afbreek van fenol uitgewerk. Daar is bevind dat bensokinoon gevorm het, wat later oksidasie ondergaan het om karboksielsure te vorm.
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Rogerson, Martin. "An NMR study of molecular dynamics in organic crystalline compounds." Thesis, University of St Andrews, 1995. http://hdl.handle.net/10023/14804.
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Using a combination of solid-state NMR techniques including Tip measurements, dynamic line shape analyses and 2D EXSY data, a variety of intramolecular motions including rotations of methyl, t-butyl, t-amyl, phenyl, trimethylammonium and trimethylphosphonium groups in a series of quaternary ammonium and phosphonium salts have been investigated. Where possible, activation parameters Ea, △G+/-, △H+/- and △S+/- have been derived. A range of values was recorded, especially for △S+/- which ranged from +75 JK−1 mol−1 for a phenyl group to -57 JK−1 mol−1for a t-butyl group. It was shown that 13p and 31p T1p measurements from CP/MAS spectra can give quantitative information on the kinetics of intramolecular motions that agree with line shape analysis. Recent work using X-ray crystallography has suggested that some derivatives of bicycle [3.3.1] nonane show evidence of conformational equilibria in the solid state. Using 13CP/MAS NMR, 22 derivatives of bicycle [3.3.1] nonane were studied, some at variable temperature. No evidence of conformational equilibria was observed in the chosen compounds. Solid-state NMR has been used to follow the kinetics of ring- chain tautomerism in a bicyclic tetrahydro-1,3-oxazine derivative. This was found to form initially the metastable chain on crystallisation, which then cyclises. The kinetics of the cyclisation were followed and the activation energy for the solid-state reaction was derived. In contrast to this, a related pyrimidine derivative has been found to form initially the metastable ring on cyclisation which quickly ring opens to the chain.
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Kruger, Elna. "Ionic liquids as media for electro-organic synthesis." Thesis, Nelson Mandela Metropolitan University, 2007. http://hdl.handle.net/10948/538.
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The IL’s used in this study were either synthesized or commercially available. Preparation of the IL’s involved 2 step processes: firstly the heating of distilled 1-methylimidazole with distilled 1-chlorobutane under reflux to obtain 1-butyl-3- methylimidazolium chloride; secondly, the metathesis reaction of sodium tetrafluoroborate with 1-butyl-3-methylimidazolium chloride to obtain 1-butyl-3- methylimidazolium tetrafluoroborate. The addition of sodium tetrafluoroborate, sodium hexafluorophosphate and lithium trifluoromethane sulfonamide with 1-butyl-3-methylimidazolium chloride produced good yields of 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide respectively. The IL’s are hygroscopic and must be stored under a nitrogen atmosphere. The IL’s were analyzed using 1H and 13C NMR analysis with CDCl3 as solvent. The physical and chemical properties of these IL’s were compared to commercial products. The physical and chemical properties compared well to reference values from the literature. The physical properties measured include the density, conductivity and electrochemical window. The electrochemical window is dependant primarily on the resistance of the cation to reduction and the resistance of the anion to oxidation. The electrochemical windows of the IL’s were very similar to the reference windows obtained from literature and it can be seen that some IL’s have a slightly lower window which can be due to water present. Water content in the IL’s was determined with the use of a Karl Fischer titrator, with Hydranal 5 Composite as titrant and HPLC grade methanol as the base. The concentration of halide in the IL’s was determined with a Perkin-Elmer ICP-MS.
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Mafatle, Tsukutlane J. P. "Homogenous and heterogenous catalytic activity of metallophthalocyanines towards electrochemical detection of organic compounds." Thesis, Rhodes University, 1998. http://hdl.handle.net/10962/d1004974.
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Cysteine plays an important role in many biological and pharmaceutical systems. Therefore, in view of its importance, it is essential to find means of detecting it at the lowest possible levels. In this regard, electrochemical techniques have been found to be capable of detecting analytes even at micro levels. However, electrochemical determination of cysteine occurs at a very high potentials. These overpotentials makes quantitative analysis or detection of cysteine difficult at most conventional carbon electrodes. On platinum electrode, the oxidation of cysteine has been reported to occur in the potential range 0.7 to 1.45 V (vs NHE). Therefore, the object of this investigative study has been to find an active complex that could replace platinum and other expensive metals as electrodes. Such a complex should also be capable of reducing the potential at which the oxidation of cysteine occurs on carbon electrodes. As a result, this manuscript gives a full report on the investigative study of electrocatalytic activity of molybdenum phthalocyanine complexes towards detection of cysteine. Molybdenum phthalocyanine, OMo(OH)Pc, and its tetrasulfonated derivative, [OMo(OH)TSPc]⁴⁻ were successfully used to reduce the potential needed to initiate the oxidation of cysteine on carbon paste electrodes (CPE). The oxidation of cysteine on CPE modified with [OMo(OH)Pc]⁴⁻ was found to occur at 0.29 V (vs Ag/AgCl), and in the presence of [OMo(OH)TSPc]⁴⁻ species in solution the oxidation occurred at 0.33 V (vs Ag/AgCl). Molybdenum, in the oxidation states of Mo(IV), Mo(V) and Mo(VI), is found in biological systems as an essential trace element, participating in a number of enzymatic reactions, where it is believed to be coordinated to sulphur-containing ligands in many molybdenum enzymes. This therefore explains why molybdenum phthalocyanines were employed in electroanalytical detection of sulphur containing amino acid, cysteine. Electrochemical methods have also been successfully used in detection of environmental pollutants such as phenolic compounds. Phenolic compounds are oxidised at readily accessible potentials. However, like cysteine, there are problems associated with the electrochemical detection of these important environmental pollutants. Their electrooxidation is known to form dimeric and/or polymeric oxidation products which adsorb onto the electrode surface, thus -videactivating it. Therefore, to address this problem, cobalt phthalocyanine (CoPc) and its tetrasulfonated derivative, [CoTSPc]⁴⁻ were employed in electrocatalytic detection of phenolic compounds. These complexes were found to increase the anodic peak currents for the oxidation of o-cresol, m-cresol, p-cresol, phenol, 2-chlorophenol and 4-chlorophenol. In addition, CoPc deposited onto the glassy carbon electrode improved the stability of the electrode, by reducing electrode poisoning caused by the electrooxidation products of the mentioned phenolic compounds. The potential at which the oxidation occurred and the current response of individual phenolic compounds depended on the degree of substitution and the type of substituent on the phenol molecule. In general, the current response was found to be lower for chlorinated phenols compared with the cresols and phenol. To establish the role of the central metal in the catalytic process, comparison of the electrocatalytic activity of some of the first row transition metal phthalocyanines, for the detection of mono-substituted phenolic compounds, showed the following trend: Co⁽¹¹⁾ > Mn⁽¹¹⁾ > Fe⁽¹¹⁾Pc > Ni⁽¹¹⁾Pc > Cu⁽¹¹⁾Pc > H₂Pc > Zn⁽¹¹⁾Pc > Bare GCE. A report is also given on electrocatalysis using [CoTSPc]⁴⁻ electrochemically deposited on the glassy carbon electrode. This was also found to enhance the anodic peak currents for the oxidation of all phenolic compounds. A report on the effects of scan rate, operating potential, analyte concentration and other variables is also given.
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Delsorbo, Carter A., Annie B. McCullough, Pau Peiro'Vila, Lyndsey B. Pulliam, Alyssa N. Rojas, Kayla M. Sager, and Dennis L. Ashford. "Ruthenium Compounds for Photodynamic Chemotherapeutics and Solar Fuel Generation." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/asrf/2019/schedule/156.
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Ruthenium polypyridyl complexes have long been studied due to their unique photophysical characteristics and their synthetic accessibility. We report here the use of new ruthenium polypyridyl’s in photodynamic chemotherapeutic and solar fuel applications. Nearly half of all chemotherapeutics administered today are derived from platinum-based drugs (platins) which lack specificity and can cause sever side-effects. Photodynamic chemotherapeutics (PDT) circumvent these issues utilizing light activation at the site of cancerous cells to generate a cytotoxic Ru(II) center and eventually trigger cellular apoptosis. The new PDT pro-drugs presented push their metal-to-ligand charge transfer (MLCT) light absorption out into the near-IR which is able to penetrate skin at greater depths than traditional PDT drugs. New Ru(II) hydrogen fuel evolution catalyst for use in dye-sensitized photoelectrosynthesis cells (DSPECs) based off of the extensively explored octahedral tridentate-bidentate coordination motif is also investigated. In particular, pendant bases are oriented toward the active site of the catalyst to increase catalytic rates and lower overpotentials. Preliminary density functional theory calculations show that strategic placement of the pendant amine on the bidentate ligand allows for productive interactions between the base and the active site of the catalyst to evolve hydrogen.
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Reis, Adriana Karla Cardoso Amorim. "Análise conformacional das α-etilsulfinil- e α-etilsulfonil-acetofenonas-para-substituídas; α-metiltio, α-dietoxifosforilacetofenonas-para-substituídas e suas formas mono- e di-oxigenadas." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/46/46135/tde-22082014-113026/.
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A presente tese relata o estudo conformacional e das interações eletrônicas de algumas: a) α-etilsulfinil- (Ia), α-etilsulfonil- (Ib) acetofenonas-para-substituídas Y-Φ-C(O)CH2SOnEt [I, n=1 (a) e n=2 (b)]; b) α-metiltio-α-dietoxifosforilacetofenonas-para-substituídas (IIa) e suas formas mono- (IIb) e di- (IIc) oxigenadas Y-Φ-C(O)CH[SOnMe][P(O)(OEt)2] [II, n=0 (a), n=1 (b)] e n=2 (c)]; c) α-bromo-α-etilsulfonilacetofenonas-para-substituídas Y-Φ-C(O)CH[Br][SO2Et] (III). Este estudo foi realizado através das espectroscopias no Infravermelho, Ressonância Magnética Nuclear, Ultravioleta e cálculos ab initio HF/6-31G**. Nas α-etilsulfinilacetofenonas-para-substituídas (Ia) a conformação cis é a preferencial para toda série, enquanto nas α-etilsulfonilacetofenonas-para-substituídas (Ib) a conformação gauche é a predominante. Nas α-metiltio-α-dietoxifosforilacetofenonas-para-substituídas (IIa) existe uma única conformação estável que apresenta o grupo (SMe) na geometria gauche e o grupo [P(O)(OEt)2] na geometria quasi-cis em relação à carbonila. As α-metilsulfinil-α-dietoxifosforilacetofenonas-para-substituídas (IIb) apresentam duas conformações estáveis, sendo cada uma delas referente a um diastereômero, tanto em solução de solventes de polaridade crescente quanto no estado gasoso. A conformação mais estável (CSSS) apresenta o grupo (MeSO) numa geometria quasi-periplanar (quasi-cis) e o grupo [(P(O)(OEt)2] numa geometria anti-clinal (gauche). A segunda conformação CRSS apresenta os dois substituintes, (MeSO) e [(P(O)(OEt)2], numa geometria sin-clinal (gauche). Nas α-metilsulfonil-α-dietoxifosforilacetofenonas-para-substituídas (IIc) a conformação preferencial apresenta os grupos (MeSO2) e [(P(O)(OEt)2] na geometria sin-clinal em relação à carbonila. As α-bromo-α-etilsulfonilacetofenonas-para-substituídas (III) apresentam-se numa única conformação estável, contendo o grupo (SO)2Et) na geometria sin-periplanar (quasi-cis) e o átomo de (Br) na geometria sin-clinal (gauche).This thesis reports the conformational and electronic interaction studies of some: a) α-ethylsulfinyl- (Ia) and α-ethylsulfonyl- (Ib) para-substituted acetophenones Y-PhC(O)CH2SOnEt [I, n=1 (a) and n=2 (b)]; b) α-methylthio-α-diethoxyphosphoryl-para-substituted acetophenones (IIa) and their corresponding mono- (IIb) and di- (IIc) oxygenated derivatives Y-PhC(O)CH[SOnMe][P(O)(OEt2)] [II, n=0 (a), n=1 (b)] and n=2 (c)]; c) α-bromo, α- ethylsulfonyl-para-substituted acetophenones Y-PhC(O)[Br][SO2Et] (III). This study was performed by means of Infrared, Nuclear Magnetic Resonance, Ultraviolet spectroscopies, ab initio computations and X-ray diffraction analysis. For the α-ethylsulfinylacetophenones (Ia) the cis conformer predominates over the gauche one while in the case of the α-ethylsulfonylacetophenones (Ib) the gauche conformer is the more stable relative to the quasi-cis one. The α-methylthio-α-diethoxyphosphoryl acetophenones (IIa) present only a single stable conformer which bears the (SMe) group in a syn-clinal (gauche) geometry and the [P(O)(OEt2)] group in the quasi-periplanar (quasi-cis) geometry with respect to the carbonyl group. The α-methylsulfinyl-α-diethoxyphosphoryl acetophenones (IIb) display two stable conformations corresponding each one to a different diastereomer. The most stable conformer CSSS presents the methylsulfinyl group [MeS(O)] in a quasi-periplanar (quasi-cis) geometry and the diethoxyphosphoryl group [P(O)(OEt2)] in a anti-clinal (gauche) geometry relative to the carbonyl group. The second less stable conformer corresponds to the CRSS diastereomer and displays both the [MeS(O)] and the [P(O)(OEt2)] groups in a syn-clinal (gauche) geometry. The α-methylsulfonyl-α-diethoxyphosphoryl acetophenones (IIc) presents only a single stable conformer bearing both the [MeSO2] and [P(O)(OEt)2] groups in a sin-clinal geometry with respect to the carbonyl group. The α-bromo-α-ethylsulfonylacetophenones III present a single stable conformation bearing the the [SO2Et] group in a syn-periplanar (quasi-cis) geometry and the [Br] atom in a syn-clinal (gauche) geometry relative to the carbonyl group.
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Hunter, James Freeman. "Oxidation of atmospheric organic carbon : interconnecting volatile organic compounds, intermediate-volatility organic compounds, and organic aerosol." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/97794.
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Thesis: Ph. D. in Environmental Chemistry, Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 101-110).
.Organic molecules have many important roles in the atmosphere, acting as climate and biogeochemical forcers, and in some cases as toxic pollutants. The lifecycle of atmospheric organic carbon is extremely complex, with reaction in multiple phases (gas, particle, aqueous) and at multiple timescales. The details of the lifecycle chemistry (especially the amount and properties of particles) have important implications for air quality, climate, and human and ecosystem health, and need to be understood better. Much of the chemical complexity and uncertainty lies in the reactions and properties of low-volatility oxidized intermediates that result from the oxidation of volatile organic precursors, and which have received comparatively little study thus far. This thesis describes three projects that link together the entire chain of oxidation (volatile to intermediate to condensed) in an effort to improve our understanding of carbon lifecycle and aerosol production. Laboratory studies of atmospherically relevant aerosol precursors show that the slow oxidation of intermediates is critical to explaining the yield and properties of aerosol under highly oxidized ("aged") conditions, and that the production of organic particles is significantly increased when intermediates are fully oxidized. This aging process is a strong function of molecular structure, and depends on aerosol concentration through the phenomenon of condensational trapping. Further laboratory studies of a series of (poly)cyclic 10 carbon alkanes show that structural effects are largely explained through fragmentation reactions, and that more generally, carbon-carbon bond scission is a ubiquitous and important reaction channel for oxidized intermediates. Finally, direct measurement of oxidized intermediate compounds in field studies shows that these compounds are abundant and important in the ambient atmosphere, with concentrations and properties in between those of volatile and particulate organic compounds. Together with other co-located measurements and complementary techniques, this enables estimates of emission, oxidation, and deposition to be constructed. The results from this thesis can be used to inform more sophisticated models of atmospheric organic carbon cycling, and to improve prediction of organic particulate matter concentrations.
by James Freeman Hunter.
Ph. D. in Environmental Chemistry
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Gonçalves, Márcia Regina. "Síntese, caracterização e estudo fotofísico e eletroquímico de compostos polipiridínicos de Re(I) e ciclometalados de Ir(III) e aplicação desses compostos em dispositivos eletroluminescentes." reponame:Repositório Institucional da UFABC, 2018.
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Orientadora: Profa. Dra. Karina Passalacqua Morelli FrinTese (doutorado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência e Tecnologia/Química, Santo André, 2018.
Neste trabalho foram estudadas as propriedades fotofisicas e eletroquimicas dos compostos polipiridinicos fosforescentes de Re(I), fac-[ReCl(CO)3(N^N)] e fac-[Re(PPh3)(CO)3(N^N)]+, em que N^N = 1,10-fenantrolina (phen), 4,7-dimetil-1,10-fenantrolina (Me2phen) ou 4,7-dimetoxi-1,10-fenantrolina ((MeO)2phen) e PPh3 = trifenilfosfina e dos compostos fosforescentes ciclometalados de Ir(III), mer-[Ir(ppy)2(L^X)], em que L^X= 4,4fff'-(1,4-fenileno-bis-(2,2f,6f,2ff-terpiridina)) (tpy), carboxilato de 3-iodopiridinilmetila (Ipic) e ppy = 2-fenilpiridina. Ademais, o desempenho de dispositivos eletroluminescentes emissores de luz com esses compostos foi investigado por meio da capacidade de injecao e transporte de carga e transferencia de energia entre matriz e dopante. Os compostos foram sintetizados, purificados, caracterizados por meio de espectroscopias UV-visivel, na regiao do infravermelho, IV, e ressonancia magnetica nuclear de hidrogenio, 1H RMN. Os compostos de Re(I) e Ir(III) se encontram nas conformacoes facial e meridional, respectivamente.Nos espectros de absorcao dos compostos fac-[ReL(CO)3(N^N)], L = Cl e PPh3, e mer-[Ir(ppy)2(L^X)] foram observadas duas regioes: uma de mais alta energia, atribuida as transicoes intraligantes (IL) e, uma de menor energia, atribuida as transicoes de transferencia de carga do metal para o ligante (MLCT). Foi investigada a emissao desses compostos em solucao e em meio rigido, que pode ser atribuida ao estado excitado triplete de energia mais baixa. Para os compostos de Re(I), a temperatura ambiente, essa emissao pode ser atribuida principalmente ao estado excitado triplete de transferencia de carga do metal para o ligante polipiridinico (3MLCTRe¨N^N*) e que, em meio rigido, apresenta um maior carater do estado excitado triplete centrado no ligante (3IL), observando-se a inversao entre esses estados para os compostos com os ligantes polipiridinicos Me2phen e ((MeO)2phen. Para os compostos de Ir(III), a temperatura ambiente, a emissao pode ser atribuida ao estado excitado triplete de transferencia de carga do metal para o ligante auxiliar 3MLCTIr+ppy¨L^N, e que, em meio rigido, para o composto mer-[Ir(ppy)2(Ipic)], ocorre a inversao entre os estados 3MLCT e 3IL e, portanto, a emissao e atribuida a este ultimo estado excitado. Os tempos de vida obtidos para os compostos de Re(I), 0,18-2,52 ¿Ês, e de Ir(III), 60 ns - 0,43 ¿Ês, sao consistentes com estados emissores tripletes. Os rendimentos quanticos, constantes de decaimento radiativas e nao radiativas, potenciais de oxidacao e reducao tambem foram avaliados. Os calculos dos niveis de energia HOMO (highest occupied molecular orbital) e do LUMO (lowest unoccupied molecular orbital) foram realizados e comparados aos do polimero poli(vinil)carbazol (PVK).
In this work, both photophysical and electrochemical properties of phosphorescent polypyridyl Re(I) compounds, fac-[ReCl(CO)3(N^N)] and fac-[Re(PPh3)(CO)3(N^N)]+, N^N = 1,10-phenanthroline (phen), 4,7-dimethyl-1,10- phenanthroline (Me2phen) and 4,7-dimethoxi-1,10-phenanthroline ((MeO)2phen) and PPh3 = triphenylphosphine and phosphorescent cyclometalated Ir(III) complexes, mer-[Ir(ppy)2(L^X)], where L^X= 4¿,4¿¿¿¿-(1,4-Phenylene)bis(2,2¿:6¿,2¿¿-terpyridine) (tpy), 3-iodopyridine-2-carboxylate (Ipic) e ppy = 2-phenylpyridine, were investigated. Furthemore, the performance of electroluminescent devices by means of the charge injection ability was investigated as well as transport and energy transfer between the host and guest. These compounds were synthesized, purified and characterized by Uv-visible, infrared and proton nuclear magnetic resonance, 1H NMR, spectroscopies. Re(I) and Ir(III) compounds are in facial and meridional geometries, respectively. In the absorption spectra of the fac-[ReL(CO)3(N^N)], L = Cl and PPh3, and mer-[Ir(ppy)2(L^X)] are observed two bands: the higher energy one, assigned to intraligand transitions (IL), and the lower energy one, assigned to metal to ligand charge transfer (MLCT) transition. The emission of the compounds was investigated in fluid and rigid media, which could be ascribed to the low-lying triplet excited state. For the Re(I) compounds, at room temperature, the emission is characteristic of the triplet metal-to-ligand charge transfer (3MLCTRe¨N^N*) and, in rigid media, shows some degree of the triplet ligand-centered (3IL) emission, observing the inversion between these states for the compounds with the polypyridine ligands Me2phen and (MeO)2phen. For the Ir(III) compounds, at room temperature, the emission could be assigned to the triplet low-lying metal-to-ligand charge transfer 3MLCTIr+ppy¨L^N, and, in rigid media, for the mer-[Ir(ppy)2(Ipic)] compound occurs the inversion between the 3MLCT and 3IL excited states, therefore, the emission is ascribed from the latter excited state. The lifetime obtained for the the Re(I) compounds, 0.18-2.52 ¿Ês, and for the Ir(III) compounds, 60 ns - 0.43 ¿Ês, are consistent with triplet excited states. The emission quantum yields, radiative and non-radiative rates, oxidation and reduction potentials were also evaluated. The calculations of the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energy levels were performed and the values compared to the poly(vinyl)carbazol polymer (PVK).
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Zhou, Xiaofei. "The electrochemistry of organic nanoparticles." Thesis, University of Oxford, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.728824.
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Ojala, S. (Satu). "Catalytic oxidation of volatile organic compounds and malodorous organic compounds." Doctoral thesis, University of Oulu, 2005. http://urn.fi/urn:isbn:9514278704.
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Abstract
This thesis describes efforts made on the development of an existing catalytic incinerator. The development work, called process characterization, consists of four general parts. These are the development of measurement methodology, the studying of construction materials, the selection of suitable catalysts and the testing of the effects of process operation conditions. The two application areas for catalytic incineration considered in this thesis are solvent emission abatement (VOC, volatile organic compounds) and chip bin emission abatement (SVOC, sulphur-containing volatile organic compounds).
As a baseline, the process characterization is started with the development of measurement methodology. In general, the methodology will decrease costs and simplify the carrying out of the actual measurements and thereby make the measurement time more effective. In the methodology it is proposed that continuous total concentration measurement should be used in connection with qualitative sampling to obtain reliable measurement data.
The selection of suitable construction materials for the application is very important. As shown in this thesis, the end conversions in solvent emission abatement may even be improved through the selection of the proper construction materials. In chip bin emission abatement, the problem arises from corrosive oxidation products that set limits on the construction materials used as well as on oxidation conditions.
Catalyst selection is based on the following catalytic properties: activity, selectivity and durability. These catalytic properties are studied either at the laboratory or on an industrial scale. The catalytic materials tested are Pt, Pd, Pt-Pd, Cu-Mn oxides, MnO2-MgO, CuxMg(1-x)Cr2O4 and CuxCr2O4. The most important selection criteria in solvent emission abatement are proposed to be activity and selectivity. In the case of chip bin-SVOC-abatement, these are selectivity and durability. Based on these criteria, catalysts containing Cu-Mn oxides and Pt were demonstrated to be the best catalysts in VOC oxidation, and catalyst containing MnO2-MgO was shown to be best catalyst in SVOC oxidation.
A study on the effect of process operation parameters (temperature, concentration and gas hourly space velocity (GHSV)) and moisture was carried out with the aid of factorial design. In VOC (n-butyl acetate) oxidation, the most influential process parameter was GHSV, which decreased the end conversion when it was increased. In SVOC (DMDS) oxidation, the effect of temperature was most significant. The end conversions increased as the temperature increased. Moisture slightly decreased the formation of by-products in n-butyl acetate oxidation. In DMDS oxidation, moisture slightly increased the end conversions at a lower temperature level (300°C).
At the end of the thesis, these process parameters are also discussed from the standpoint of the catalysts' activity, selectivity and durability. Finally, proposals for process improvements are suggested.
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Taylor, Paul. "Organic thionitroso compounds." Thesis, Durham University, 1989. http://etheses.dur.ac.uk/6482/.
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A series of novel N-substituted phthalimide-2-sulplienamides was prepared. The N-aryl analogues were shown to be efficient precursors to thionitrosoarenes. Extension of the methodology to heteroaroraatic and acyl derivatives was unsuccessful, with the exception of 3-thionitroso- pyridine, the first known thionitrosoheteroarene. Thionitrosoarenes are shown to be versatile dienophiles and enophiles. Reactions with various substituted dienes proceeded with high stereoselectivity and some regioselectivity to afford 3,6-dihydro- 1,2-thiazines. Cycloadditions of thionitrosoarenes generated independently from imidosulphurous chloride precursors showed similar selectivities. The mechanism of cycloaddition is discussed in the light of molecular orbital calculations.
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Oey, Ching-ching. "Organic-inorganic nanocomposites for organic optoelectronic devices." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B35321222.
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Oey, Ching-ching, and 黃晶晶. "Organic-inorganic nanocomposites for organic optoelectronic devices." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B35321222.
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Korell, Ulrich. "Electrochemistry at organic conducting salt electrodes." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61171.
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Sephton, Mark A. "Organic compounds in meteorites." Thesis, Open University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339860.
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Kalaji, M. H. "Mechanistic and synthetic studies in organic electrochemistry." Thesis, University of Southampton, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355159.
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Szecsödy, James Edward. "Sorption Kinetics of Hydrophobic Organic Compounds onto Organic Modified Surfaces." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/219433.
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The sorption of five chlorinated benzenes and sixteen other organic solutes was investigated by determining the extent of sorption and the sorption rates in a series of 40 batch and 139 column experiments using surface-modified silica of known chemical composition. These surfaces were used to represent important functional groups in soil, and consisted of porous silica with patchy surface coatings of aliphatic chains (C₁, C₈, and C₁₈), and other substituent groups (phenyl, amine, alcoholic, and carboxylic). Three possible rate-limiting steps were examined: diffusion through immobile pore fluid, diffusion through bound organic matter, and the chemical binding and release rate. First-order desorption rate coefficients were observed to be 10⁻¹ to 10⁻² s⁻¹ on unbonded, and C₈, C₁₈, amine, and alcoholic modified surfaces, and 10⁻³ to 10⁻⁵ s⁻¹ on C₁ and phenyl-polymer modified surfaces. Diffusion through immobile pore fluid had only a minor effect on the sorption rate, as evidenced by similar rates on organic-bound porous and solid particles. The diffusion rate through the bound organic layer is not rate limiting due to the small organic layer thickness. The observed slow desorption on the phenyl-polymer surface is consistent with the rate limiting step being the chemical binding and release rate. The changes in the rate with temperature and within a series of chlorinated benzenes support this conclusion. The free energies for sorption onto the phenyl-polymer surface ranged from -4.0 kcal mol⁻¹ for chlorobenzene to -6.9 kcal mol⁻¹ for pentachlorobenzene, which are within the range expected for van der Waals interactions. The observed sorption energies are slightly stronger than predicted for hydrophobic surfaces, possibly reflecting strong binding due to multiple pi-pi electron interactions on the phenyl-polymer surface. Hydrophobic solute partitioning onto natural soils, as observed by others, is less than that observed on aliphatic and phenyl hydrophobic surfaces in this study, but greater than on amine or alcoholic modified surfaces. The sorption of di-, tri-, and tetra-chlorobenzenes onto the phenyl-polymer surface is apparently driven by the overall sorption enthalpy (ΔH° = -3.9 to -4.9 kcal mo1⁻¹) and to a lesser extent by the entropy (TΔS° = 0.5 to 1.5 kcal mol⁻¹). As equilibrium of the reactions observed in this study are reached within hours, these reactions are important at small field scales where residence times are hundreds of hours or less.
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Ye, Penglin. "Semi-Volatile Organic Compounds: Behavior and Secondary Organic Aerosol Formation." Research Showcase @ CMU, 2015. http://repository.cmu.edu/dissertations/1046.
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This thesis mainly described the development of studying the behavior and secondary organic aerosol formation from semi-volatile organic compounds (SVOCs). SVOCs comprises a significant fraction of the organic mass in particulate matter (PM), which has shown important impacts on human health and also influences on Earth’s climate. SVOCs are thought to play essential roles in the formation of SOA, chemical aging and mixing processes. Smog chambers have been extensively used to study SOA formation, chemical reaction and physical properties. The interaction between SVOC vapor with Teflon chamber wall and suspended particles is a key factor influencing organic aerosol formations and behaviors in chamber experiments. We observed that pinanediol (PD) showed a large chamber wall deposition and reached a steady concentration, only around 14% of mass left in the gas phase. But we did not observe the release of PD from the chamber walls during isothermal dilution of the chamber with fresh air at 22 oC, which indicated there was no PD released from the chamber walls during the SOA formation. This clearly shows the vapor loss of SVOC precursors need to be considered when studying their SOA formation. The average carbon oxidation states the SOA from PD were calculated as around -0.7, which were similar to the value observed in CLOUD. Our data are consistent with ~10% of the SOA with low volatility that could drive new particle formation. It is challenging to measure SVOC vapor concentrations and properties. A new approach is discussed in this thesis, studying SVOC vapors from measuring the particles. The SVOCs coated particles sustained the SVOCs in the gas phase at or near their saturation concentration. The mass loss of SVOCs from the suspended particles thus reflects SVOCs vapor wall loss. Our results show the vapor wall loss rate of SVOC is consistently proportional to the SVOC vapor concentrations. We observed PEG400 seeds can sorb semi-volatile α-pinene SOA vapors. This allows us to trap semi-volatile α-pinene SOA into PEG400 seeds and then analyze their compositions and properties through measuring particles. PEG400 is liquid, water-soluble, nearly non-volatile, good solvent for SOA and relative stable during the oxidation with OH radicals and ozone. It can also be easily separated from the SOA mass spectrum with the unique fragment C4H9O2+ at m/z=89. The results demonstrated that SOA prepared from α-pinene reacted with OH produced more semi-volatile SOA vapors comparing to α-pinene ozonolysis. More semi-volatile SOA vapors were observed in the gas phase with higher SOA loadings. With well-built particle measurement methods, we may get more knowledge on the SVOC vapors.
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Ndamyabera, Christophe Adrien. "Porous metal-organic frameworks for sorption of volatile organic compounds." Doctoral thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/33877.
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Metal-organic frameworks (MOFs) present potential for various applications such as gas sorption, gas storage, sensing, drug delivery, and catalysis. This attracts researchers to design and synthesize MOFs that can respond to a specific application. In this thesis, mixed ligands 34pba and 44pba ligands (34pba = 3-(4-pyridyl)benzoate, and 44pba = 4-(4-pyridyl)benzoate) and Co2+ metal salts were used to synthesize porous MOFs {[Co(34pba)(44pba)]·DMF}n (1) and {[Co(34pba)(44pba)]·(C3H6O)}n (2), with DMF = N,N'-dimethylformamide and C3H6O = acetone through solvothermal reaction. These two relate to each other through hinge-like expansion or contraction of the guest-accessible void. The use of Zn2+ as a metal ion led to an isostructural MOFs [Zn(34pba)(44pba)]·DMF}n (3) of 1. Using 34pba as a single ligand and Cu2+ as the metal ion led to the formation of a 2D [(Cu(34pba)2]·DMF) (4) while a little variation of solvent mixture resulted in a 3D {[CuCl2(34pba)2]∙solvent}n (7) structures. The functionalized ligands 44paba and 34paba (34paba = 3-(pyridyn-4-ylmethyl)aminobenzoate, 44paba = 4-(pyridyn-4- ylmethyl)aminobenzoate) were used with Cu2+ centre to prepare [Cu(44paba)·(H2O)·(DMF)]n (5) and {[Cu3(34paba)5(H2O)2]·(DMF)2}n (6), both of which are 1D structures. The activated MOFs 1d and 3d from (1 and 2) were used for the adsorption of volatile organic compounds (VOCs) and gases. In all tested guest molecules, there was higher sorption capacity in 1d which could be attributed to some gate opening process occurring which does not occur in 3d. Some effects responding to the sorption such as the change of colour in 1d were characterized. This colour change may be associated with the d-d, metal to ligand charge transfer, or π to π* transitions in coordination complex. Crystal structures and their stability, sorption properties and selectivity were characterized by single crystal X-ray diffraction, thermogravimetric analysis, differential scanning, hot stage microscopy, powder X-ray diffraction, infrared spectroscopy, and proton viii nuclear magnetic resonance (1H NMR) analysis. This thesis also reports the effect of methanol on discrete complexes of cis-dichloro-bis(ethylenediamine)cobalt(III) chloride (Coen) that led to the formation of a new crystal structure upon the removal of the water of hydration. The lattice energies calculated prove that Coen is more stable to allow a quick reversible sorption.
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Zappi, Guillermo Daniel. "Indirect electrochemical oxidations in organic chemistry." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252698.
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Blasucci, Vittoria Madonna. "Organic solvents for catalysis and organic reactions." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31723.
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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2010.Committee Chair: Charles Eckert; Committee Co-Chair: Charles Liotta; Committee Member: Amyn Teja; Committee Member: Christopher Jones; Committee Member: William Koros. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Sanders, Giles. "The dissolution of organic compounds." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362083.
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Budd, Laura Elizabeth. "Polymorphism in small organic compounds." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/3967.
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The effect of temperature on the crystal structure of deuterated piperidine has been studied using neutron powder diffraction. Differential scanning calorimetry indicates that there are multiple phases accessible via changes in temperature however there is no evidence of this in the neutron powder diffraction study with only one phase observed in the range 2 – 250 K and under various crystallisation conditions. The effect of pressure up to 2.79 GPa has also been determined. The compression of the structure is facilitated through the closing up of voids in the structure and no phase transition is observed. Differential scanning calorimetry has shown N-methyl and N,N-dimethylformamide both exhibit a thermal event prior to melting. Low temperature neutron powder diffraction has shown these transitions are associated with the onset of methyl group rotation. Neutron powder diffraction studies show formamide exhibits remarkable polymorphism at ambient temperature and pressures between 0.1 GPa and 3.6 GPa, forming four new polymorphs. All the structures consist of N-H…O hydrogen bonded chains. The formation of the various polymorphs can be rationalised in terms of the orientation of the molecules within the hydrogen bonded chains and the resultant structures formed by further hydrogen bonds between the chains. This is in stark contrast to the effect of varying conditions of temperature where only one structure exists from 2 K right up to the melting point. The effect of temperature on the crystal structure of pyrazine in the range 8 – 315 K is described. At temperatures below 90 K the structure undergoes a phase transition to a previously uncharacterised phase, designated phase IV, which is closely related to the previously known phase I. The crystal structure of phase III has been determined at 315 K. The crystal structure of pyrazine has been determined at room temperature at pressures between 0.11 GPa and 9.36 GPa. At 0.94 GPa a transition from phase I to phase IV is observed. This is the same phase as observed at low temperatures. Crystal growth at 215 K results in the formation of two different phases of mesitylene; phase II and a new previously unknown phase designated phase IV. The structure of phase IV has been determined and found to be stable in the range 90 – 221 K. On cooling a crystal of deuterated mesitylene in phase II to 90 K a transition to phase III was observed and the resultant crystal structure is closely related to that of phase II.
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Matqi, Khalil Yacoub. "Biodesulphurisation of organic sulphur compounds." Thesis, University of Sheffield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251215.
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Compagnone, D. "Amperometric sensors using organic compounds." Thesis, Cranfield University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386197.
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Shek, Lai Yung. "Hydrothermal crystallization of organic compounds /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202004%20SHEK.
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Ocampo, Ana Maria. "Persulfate activation by organic compounds." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Dissertations/Summer2009/A_Ocampo_083109.pdf.
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Thesis (Ph. D.)--Washington State University, August 2009.Title from PDF title page (viewed on Sept. 9, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references.
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Said, Elias. "Electrolyte : Semiconductor Combinations for Organic Electronic Devices." Doctoral thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15775.
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The discovery of semi-conducting organic materials has opened new possibilities for electronic devices and systems because of their solution processibility, lightweight and flexibility compared to inorganic semiconductors. The combination of semiconductors with electrolytes, and more especially organic semiconductors and solid electrolytes has attracted the attention of researchers because of the multiple phenomena originating from the simultaneous motion of electrons and ions. This thesis deals with organic-based devices whose working mechanism involves electrolytes. By measuring electrochromism induced by the field in isolated segments of conjugated polymer films, which is in contact with an electrolyte, the direction and the magnitude of the electric field along an electrolyte is quantified (paper I). In addition, using a polyanionic proton conductor in organic field-effect transistor (OFET) as gate dielectric results in low operation voltage and fast response thanks to the high capacitance of the electric double layer (EDLC) that is formed at organic semiconductor/ polyelectrolyte interface (paper III). Because an electrolyte is used as a gate insulator, the effect of the ionic currents on the performance of an EDLC-OFET has been investigated by varying the relative humidity of the device ambience (paper IV). Since the EDLC-OFET and the electrochromic display cell both are operated at low voltages, the transistor has been monolithically integrated with an electrochromic pixel, i.e. combining a solid state device and an electrochemical device (paper V). Further, a theoretical study of the electrostatic potential within a so called pen-heterojunction made up of two semi-infinite, doped semiconductor media separated by an electrolyte region is reported (paper II).
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Felix, Fabiana da Silva. "Novos materiais para aplicações analíticas nas determinações de compostos orgânicos de interesse farmacêutico e ambiental." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-30072009-090507/.
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Sensores de filme de carbono, construídos a partir de resistores com 2 Ω de resistência nominal, foram utilizados para aplicações em áreas de interesse ambiental e farmacêutico sem a modificação prévia de suas superfícies. Através de um tratamento eletroquímico em meio ácido, é possível obter uma faixa de potencial (para ambos os limites anódico e catódico) maior comparado aos eletrodos de carbono convencionalmente utilizados. Devido ao fato dos sensores serem confeccionados em escala industrial na Alemanha, seu custo é muito baixo, tornando possível sua utilização na forma de eletrodos descartáveis. Além disso, são caracterizados por uma grande versatilidade, reprodutibilidade e estabilidade. Para comprovar a viabilidade dos eletrodos de filme de carbono como transdutores voltamétricos, amostras de paraquat foram analisadas em águas de rio e potável. A associação com a voltametria de onda quadrada possibilitou obter um limite de detecção inferior ao limite máximo estabelecido para o herbicida em água potável. Estudos por voltametria cíclica mostraram dois picos para a redução do paraquat, similares aos descritos na literatura. Os sensores de filme de carbono também foram adaptados ao sistema de análise por injeção em fluxo para a determinação amperométrica de paracetamol e de ambroxol em formulações farmacêuticas. Em ambos os estudos, foi possível obter ampla faixa linear de concentração, baixos limites de detecção e sensibilidade elevada. Estudos de repetibilidade com os dois analitos apresentaram desvios padrões relativos de até 3%, comprovando a ausência de efeito de memória. Os resultados obtidos durante as análises em fluxo com os novos sensores amperométricos concordaram com as metodologias descritas nas farmacopéias. Ao longo dos quatro anos de doutoramento também foram desenvolvidos outros estudos, os quais estão descritos nos apêndices desta tese.Carbon film sensors, built from resistors of 2 Ω nominal resistance, were employed for application in the environment and pharmaceutical fields without previous modification of the electrode surface. When these sensors are electrochemically treated they obtain a wider potential window (both anodic and cathodic regions) than many other forms of carbon. Due to the fact that sensors are produced on industrial scale in Germany, the cost of each unit is very low, a feature that enables the use of these electrodes in disposable form. Moreover, they have great versatibility, reproducibility and stability. To prove the suitability of the carbon film electrodes as voltammetric sensors paraquat samples were analysed in river and drinking water. The association with the square wave voltammetry led to a detection limit below the allowed upper limit for herbicide analysis in drinking water. Previous results with cyclic voltammetry showed two peaks for paraquat reduction, in agreement with the literature data. The carbon film sensors were also adapted to the flow injection analysis system for amperometric determination of acetaminophen and ambroxol in pharmaceutical formulations. It was possible to obtain a wide linear working range, low detection limit and high sensitivity for both analytes. During the repeatabilty studies, acetaminophen and ambroxol showed relative standard desviations lower than 3% without any memory effect. The results obtained with a new amperometric sensor associated to FIA were in good agreement with those recommended by pharmacopoeias. In the appendices of this thesis are described other studies which have been developed for four years of PhD.
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Forsyth, Stewart Alexander 1975. "Novel organic salts." Monash University, School of Chemistry, 2003. http://arrow.monash.edu.au/hdl/1959.1/5833.
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Reinheimer, Eric Wade. "Hybrid inorganic-organic, organic charge transfer, and radical based compounds with chalcofulvalene donors and organic acceptors." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-2452.
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Newington, Ian M. "Azo-anions in organic synthesis." Thesis, University of Oxford, 1985. http://ora.ox.ac.uk/objects/uuid:690ab891-be13-4582-a029-47974d20adac.
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Novel synthetic applications of ambident azo-anions derived from hindered hydrazones have been investigated. Reaction with electrophiles occurred predominantly at carbon as the N-addition pathway was sterically retarded. Trityl, diphenyl-4-pyridylmethyl (DPP) benzhydryl, and t-butyldiphenylmethyl (BDP) hydrazones of various aldehydes and ketones were prepared in good yields from the corresponding hydrazines and carbonyls in aqueous methanol. The lithium salts derived from trityl and DPP hydrazones, by treatment with methyl lithium at -55°C, reacted with aldehydes and ketones to generate azo-alkoxides. These could be diverted to alcohols,by sequential protonation and spontaneous homolysis (about -20°C) in the presence of ethanethiol, or to alkenes,by treatment with phosphorus trichloride at -78 G followed by azo-homolysis. The reactions enabled efficient reductive cross-coupling of aldehydes and ketones. The mechanism of the alkene forming reaction was investigated. Anions of benzhydryl hydrazones were found to react inefficiently by a G-addition pathway giving mainly N-addition products. Anions of BDP hydrazones conveniently gave excellent yields of azo-alkanes upon treatment with alkyl halides,but no products were obtained on reaction with carbonyl electrophiles. The azo-alkanes could be isolated and purified and acted as key intermediates for several synthetically useful transformations. Homolysis in refluxing benzene with thiophenol gave alkanes in good yields. Phenylselenenyl-, bromo-, and chloro-alkanes,and β-alkylstyrenes were generated when thiol was replaced by diphenyl diselenide, N-bromosuccinimide, N-chlorosuccinimide and β-nitrostyrene respectively. Treatment of the azo-alkanes with trifluoroacetic acid generated benzophenone alkylhydrazones. These were dissolved in ethanol with concentrated hydrochloric acid, thereafter hydrolysis yielded alkylhydrazines or treatment with hydrogen (1 atm., 50°C, 20h) over 10% Pd/C generated primary amines by a novel use of carbonyls as α-aminocarbanion equivalents.
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Tan, Swee Hain. "Organic corrosion inhibitors." Murdoch University, 1991. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20060818.150145.
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The overall aims of this thesis were to conduct a broad survey of possible organic
corrosion inhibitors in near-neutral chloride solutions and to elucidate the
mechanisms of such action.
Altogether, 130 organic compounds were studied as possible corrosion inhibitors for
pure iron, mild steel, copper and aluminium in aerated near-neutral (pH = 8.4)
solutions containing 500 ppm NaCl and 100 ppm NaHCO,, conditions often
encountered in water-based automotive engine coolants. Inhibitor behaviour was
investigated using steady-state electrochemical techniques including polarisation
curves, Stern-Geary and corrosion potential (Em,) measurements.
The organic compounds examined were found to be highly specific in their
inhibitive action toward the metals studied. Typical examples of highly effective
corrosion inhibitors were: sebacate and octanoate for pure iron; oleate and sebacate
for mild steel; benzotriazole and 2-mercaptobenzothiazole for copper; and laurate
and oleate for aluminium.
E, was found to provide a rapid and convenient screening test for evaluating the
inhibitor performance of organic compounds toward pure iron, mild steel and
aluminium but was less useful for copper.
Good organic inhibitors were found to act as anodic inhibitors toward pure iron and
mild steel but as anodic or mixed-type inhibitors toward copper. For aluminium,
the majority of the compounds studied were found to act as anodic inhibitors.
However,However, it was also found that only pit initiation was inhibited, i.e. existing pits
were not prevented from developing. Optical microscopy of pitted aluminium
surfaces indicated their nature varied considerably with inhibition efficiency.
The role of complex formation in organic corrosion inhibitors was found to vary
with the metal. Complexation of either iron(I1) or iron(II1) ions was found to have
an insignificant effect on mild steel. The corrosion rate of copper was found to
increase with the copper(LI) complex stability, thus indicating complex formation to
be the rate-determining step. For aluminium, the observed effects were found to
depend on complex stability. For weak to moderate complexants, inhibitor
efficiency (measured as E,,) increased with increasing complexation. However, very
strong complexing agents were sufficiently stable to dissolve the aluminium oxide
surface, leading to poor inhibition. Aluminium pit morphology was found, using
scanning electron microscopy, to change from hemispherical in the uninhibited
solution to irregular in the presence of complexing inhibitors.
No simple relationships between inhibitor efficiency and molecular structure were
found. However, carbon chain length, the nature of functional group(s) and their
location in the molecule were found to be important but varied according to the
metal.
The inhibiting ability of sebacate (a straight chain C, dicarboxylate) was found not
to be compromised by water movement (stirring) or pre-existing corrosion product
layers. Immersion tests showed that passive film formation on mild steel in
sebacate solution involved two stages and was complete only after -100 h
immersion.
The ion selective properties of several iron(II1) carboxylates and hydrated iron(II1)
oxide films were studied by membrane potential measurements in neutral sodium
chloride solutions. Some specimens were also studied by Mossbauer spectroscopy.
These results show that dicarboxylates are good inhibitors toward mild steel because
they form impermeable films. Poor inhibitor performance is associated with the
anion selectivity of the film which in turn appears to be related to the film purity.
A model is suggested for the inhibition mechanism of mild steel corrosion by
dicarboxylates in aerated near-neutral chloride solutions.
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Öman, Cecilia. "Emissions of organic compounds from landfills /." Stockholm : Tekniska högsk, 1998. http://www.lib.kth.se/abs98/oman0604.pdf.
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Yang, Gang. "Aqueous solubility prediction of organic compounds." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/298795.
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Aqueous solubility is one of the most important physical properties to consider in drug discovery and development. Drug candidates with poor solubility often have poor bioavailability, which leads to increased developmental cost and efforts. Therefore, there is a strong trend to perform solubility screening of drug candidates as early as possible in the drug discovery and development process. While experimental methods are being developed to increase the throughput of solubility measurement, the development of aqueous solubility prediction methods can be a powerful complementary tool. This dissertation starts by compiling a large collection of aqueous solubility data for organic compounds covering diverse classes of structures. The data set is first used to critically evaluate the General Solubility Equation (Yalkowsky et al., 1980, 1999), one of the most widely used methods for aqueous solubility prediction. The General Solubility Equation performs very well overall as measured by the average absolute error (AAE) of 0.56 log unit. Detailed analyses indicate that it gives better predictions for non-electrolytes than some classes of weak electrolytes. This method is then compared with a method based on an amended solvation energy relationship, which considers the hydrogen bonding potentials of functional groups. It is shown that averaging the prediction results from the two methods gives better prediction than either method alone. Following the concept of the AQUAFAC model developed by Myrdal et al. (1992, 1993, 1995), an extended version of the original structural fragmentation scheme is developed. The model is trained on the data set and has an R2 value of 0.881 and a standard error of estimation of 0.819 log unit. Group contribution parameters for a set of 104 fragments are obtained. A new group contribution model is developed to suit the needs in the early drug discovery stage, when melting information is generally not available. Calculated octanol-water partition coefficient is included in the model. The model has a standard error of estimation of 0.814 log unit. When evaluated on independent test sets, the new model provides comparable prediction results with the other two models. The independence of the new model of experimental melting information makes it a suitable tool for aqueous solubility screening in early drug discovery.
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Greenacre, Caroline M. "Tropospheric chemistry of halogenated organic compounds." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404120.
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Kinnison, David J. A. "Tropospheric chemistry of halogenated organic compounds." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240663.
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Ntainjua, Ndifor Edwin. "Catalytic oxidation of volatile organic compounds." Thesis, Cardiff University, 2007. http://orca.cf.ac.uk/54585/.
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Polycyclic aromatic hydrocarbons (PAHs) are an important class of volatile organic compounds (VOCs) which pose enormous health and environmental threats. This thesis investigates different catalyst formulations for the complete oxidation of naphthalene (Np). a model PAH. Low loadings of vanadium added during the impregnation step of catalyst preparation were found to enhance the naphthalene oxidation activity of Pd-alumina and Pt- alumina catalysts while higher loadings were detrimental to the catalysts' performance. The promotional effect has been attributed to the presence of a low concentration of a particular type of vanadium species which fosters the redox behaviour of the binary system (Pd/V or Pt/V) coupled with the change in the active metal (Pd or Pt) particle size (Pd or Pt dispersion). The presence of high concentrations of crystalline V2O5 species has been suggested to account for the lower activity observed for Pd/V and Pt/V catalysts with vanadium loadings in the range of 6 - 12% and 1 - 12 % respectively. It is postulated that the mechanism of naphthalene oxidation over Pd/V differs from the mechanism of oxidation over Pt/V catalysts. The nature of support material was established to be crucial for the activity of Pt- supported catalysts for naphthalene oxidation. The Pt dispersion, metal-support interaction (MSI) and oxidation state of Pt varied as a function of the nature of support and hence resulted in differences in the Np oxidation efficiency of five Pt- supported catalysts with equal Pt loading but different supports. Low Pt dispersion (high Pt particle size), weak MSI and metallic state of Pt favoured Np oxidation. Si02 proved to be the best amongst five Pt supports investigated for Np oxidation. A variation in the preparation method and preparation conditions of ceria affected the surface area, crystallite size, oxygen defect concentration, morphology and surface reducibility of the ceria catalyst and hence the Np oxidation activity. High surface area, small crystallite size, and high oxygen defect concentration of Ce02 favoured the activity of the catalyst for Np oxidation. The best preparation methods in this study were found to be homogeneous precipitation with urea (UR) and precipitation with the carbonate (CR). Optimum preparation conditions for ceria (UR) were established and a highly active nano-crystalline ceria catalyst for Np oxidation was derived. The addition of low and high loadings of Pt during the precipitation of this ceria (UR) catalyst resulted in less active naphthalene oxidation catalysts. The drop in activity of ceria with Pt doping has been attributed to a strong metal support interaction between Pt and ceria which limits the ease at which lattice oxygen is consumed in the Mars-Van krevelen redox cycle.
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Reynolds, Stephen J. "Carbamoylcobalt (III) compounds in organic synthesis." Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280294.
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This thesis describes the development and use of organocobalt (III) compounds in the formation of carbon-carbon and carbon-heteroatom bonds and, in particular, details the application of this chemistry for the synthesis of functionalised amides and ~, 1" and 8-lactams. Organocobalt chemistry was born from the isolation and characterisation of the vitamin B12 coenzyme (2) in the 1950s and early 1960s. The introduction to this thesis covers the search for vitamin B12 and briefly describes its biological role. Next, the considerable development of the simple vitamin B12 analogues, i.e. organocobalt (II) salophens (10), is outlined. Finally, the exploitation of organocobalt (III) complexes in synthetic organic chemistry is detailed. The preparation of nitrogen heterocycles is initially addressed, with a study of the viability of carbamoylcobalt (III) salophen compounds, i.e. (68), as sources of carbamoyl radicals, i.e. (73), in Chapter 1 of the thesis. Thus, radical quenching, employing several heteroatom trapping agents, successfully afforded the amide derivatives (74) and (75). In addition, carbamoyl radicals were induced to undergo intermolecular oxidative additions to deactivated alkenes, under both thermal and photolytic conditions, to secure the cinnamamides (77) and (78). A unique approach to /3-, y- and o-lactams using cobalt-mediated radical chemistry is described in Chapter 2. Thus, the carbamoylcobalt (m) salophen (111) underwent sequential homolysis, 4-exo-trigonal radical cyclisation, and radical-cobalt (II) recombination, to create the unusual azetidin-2-one (114), which was subsequently transformed into the alcohol (125). Computer generated molecular modelling calculations supporting the novel radical cyclisation are presented. Next, analogous cyclisations are described with the homologous carbamoylcobalt (III) salophens (138) and (150). Subsequent in situ dehydrocobaltation secured the y-lactams (140) and (141), and the 8-lactams (151) and (152). Results concerning the introduction of oxygenation in tandem with cyclisation are also presented in Chapter 2. Chapter 3 of the thesis describes a novel synthetic approach to the broad-spectrum antibiotic (+)-thienamycin (56), harnessing a cobaltmediated 4-exo radical cyclisation as the key step. Model studies showed that the cyclisation would tolerate a range of substitution around the precursor, i.e. (165) and (179), and that the stereochemical outcome delivers the required 3,4-trans geometry for thienamycin, i.e. (187)~(182). Our initial synthetic target towards (56) was the acid (196), but the route was abandoned when the carbamoyl chloride (193) failed to yield the organocobalt (III) compound (194) on treatment with sodium cobalt (I) salophen (12). However, our second approach was successful and culminated in the preparation of the /J-lactam (200), which constituted a fonnal synthesis of (+)-thienamycin. Our synthetic route to (200) involved: (i) the preparation of the amine (197) via Wittig methodology, i.e. (203)~(205); (ii) conversion of (197) to the radical precursor (198); (iii) a 4-exo radical cyclisation to afford the 3,4-transazetidin- 2-one (199) and finally, (iv) a two step sequence to yield the /3- lactam (200).
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Greyling, Guillaume Hermanus. "Negative thermal expansion of organic compounds." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/6896.
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Thesis (MSc)--Stellenbosch University, 2011.ENGLISH ABSTRACT: The primary objective of the work was to investigate the negative thermal expansion of organic materials and to determine the mechanisms governing this phenomenon by using the principles of crystal engineering. To this end, the following three compounds were studied in detail: • 4,4'-Diiodobiphenyl • 4-Iodobenzoic acid • Methyl Paraben The rationale behind this work was to determine the mechanisms responsible for the observed negative thermal expansion and to uncover the structural factors that induce negative thermal expansion. Single-crystal X-ray diffraction was employed as the primary analytical tool, owing to the unique information it can provide regarding intermolecular interactions in the solid state. A total of twenty organic compounds were analysed, of which three exhibited negative thermal expansion. Each compound employs a specific mechanism for negative thermal expansion, two of which are closely related and the third distinct.
AFRIKAANSE OPSOMMING: Die hoof doel van hierdie studie was om ondersoek in te stel in die verskynsel van ‘negative thermal expansion’ in organiese materiale en gevolglik die meganisme vas te stel deur die beginsels van kristalmanipulsie (‘crystal engineering’) te gebruik. Gevolglik was drie organise stowwe ondersoek: • 4,4'-Diiodobiphenyl /4,4'-Diiodobifeniel • 4-Iodobenzoic acid /4-Iodobensoësuur • Methyl Paraben Die redenasie hieragter is om die meganisme verantwoordelik vir die ‘negative thermal expansion’ vas te stel en die verskillende faktore wat bydra tot dit te bevestig. Enkel-kristal diffraksie word benut as die primêre analitiese tegniek as gevolg van die unieke inligting wat verkry kan word met betrekking tot die intermolekulêre interaksies. 'n Totaal van twintig stowwe is geanaliseer waarvan drie die spesifieke termisie eienskap besit. Elk van die drie stowwe het ‘n ander meganisme te vore laat kom waarvan twee baie ooreenstem en die derde verskil.
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Allpress, James David. "Microbial transformation of halogenated organic compounds." Thesis, Manchester Metropolitan University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309883.
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Kim, Byeongmoon 1957. "Asymmetric organic synthesis using organoboron compounds." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14679.
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Phenix, Brian D. (Brian Dean) 1965. "Hydrothermal oxidation of simple organic compounds." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/38186.
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Haire, Geoffrey Robert. "Ruthenium catalysed oxidation of organic compounds." Thesis, University of Cambridge, 1994. https://www.repository.cam.ac.uk/handle/1810/272775.
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Padden, Amena Nicole. "Microbial degradation of organic sulfur compounds." Thesis, King's College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264989.
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Matsuda, Takanori. "Catalytic Silaboration of Unsaturated Organic Compounds." 京都大学 (Kyoto University), 2002. http://hdl.handle.net/2433/149790.
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Badea, Silviu-Laurentiu. "Association of hydrophobic organic compounds to organic material in the soil system." Licentiate thesis, Umeå universitet, Kemiska institutionen, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-68378.
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Contaminated soils and sediments have been identified as significant secondary sources of organic contaminants. Leaching tests may be useful tools to estimate the mobility of contaminants via the water phase and thereby the risk for groundwater and surface water contamination. The influence of soil composition (peat and clay content) on the leachability was investigated in batch leaching experiments for chemically diverse hydrophobic organic compounds (HOCs: PCP, PAHs, HCB, HCHs, PCBs, and TCDD/Fs). The above mentioned compounds were analyzed by both GC-LRMS (gas chromatography coupled with low resolution mass spectrometry (GC-HRMS) and GC-HRMS (gas chromatography coupled with high resolution mass spectrometry). Also the the leachability of eleven selected PCBs from naturally aged soil (Västervik, Sweden) was investigated in relation to the composition and concentration of dissolved organic matter at different pH (2 to 9), using a pH static test with initial acid/base addition. The the composition and of dissolved organic matter (DOM) at different pH values was explored by FTIR spectroscopy. The results were evaluated by orthogonal projections to latent structures (OPLS). Generally, for all model compounds studies, the Kd-values showed a variability of 2-3 orders of magnitude depending on the matrix composition. The Kd-values of moderately hydrophobic compounds, (e.g. HCHs, PCP and Phe), were correlated mainly with the organic matter content of soil. For more hydrophobic compounds (e.g.BaA, HCB and PCB 47), the leachability decreased as the proportions of OM and clay contents increased. The Kd-values of 1,3,6,8-TCDD and 1,3,6,8-TCDF were positively correlated with peat content but negatively correlated with clay content, while for PCB 153 and PCB 155 the correlations were reversed. The log Kd-values of all target PCBs decreased with increased pH values and the log Kd-values were highly correlated with the concentration of total organic carbon (TOC) in the leachates. The FTIR analysis of DOM showed that the least chlorinated and hydrophobic PCB congeners (i.e. PCB 28) might be associated with the hydrophilic fraction (i.e. carboxylic groups) of DOM. Our study demonstrated how complex interaction between the organic matter, clay components, pH and DOC influences the leachability of HOCs in a compound-specific manner.
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Kwong, Chin Fai. "Molecularly doped organic electroluminescent diodes." HKBU Institutional Repository, 2000. http://repository.hkbu.edu.hk/etd_ra/254.
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Dutta, Somnath. "Alkylzirconium alkoxides in organic synthesis reactions with sigma- and pi-bonded organic substrates /." Online access via UMI:, 2005.
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Schubert, Jeffrey W. "The structure of bromonium, chloronium, and oxonium ions." Click here for download, 2008. http://proquest.umi.com/pqdweb?did=1537007641&sid=1&Fmt=2&clientId=3260&RQT=309&VName=PQD.
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