Journal articles: 'Organic Chemistry not elsewhere classified'

1

McCarthy, Denis M. "Proton Pump Inhibitor Use, Hypergastrinemia, and Gastric Carcinoids—What Is the Relationship?" International Journal of Molecular Sciences 21, no. 2 (January 19, 2020): 662. http://dx.doi.org/10.3390/ijms21020662.

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Neuroendocrine tumors (NETs) throughout the body are the focus of much current interest. Most occur in the gastrointestinal tract and have shown a major increase in incidence over the past 30 years, roughly paralleling the world-wide increase in the use of proton pump inhibitor (PPI) drugs. The greatest rise has occurred in gastric carcinoids (g-NETs) arising from enterochromaffin-like (ECL) cells. These tumors are long known to occur in auto-immune chronic atrophic gastritis (CAG) and Zollinger-Ellison syndrome (ZES), with or without multiple endocrine neoplasia type-1 (MEN-1), but the incidences of these conditions do not appear to have increased over the same time period. Common to these disease states is persistent hypergastrinemia, generally accepted as causing g-NETs in CAG and ZES, and postulated as having similar tumorigenic effects in PPI users. In efforts to study the increase in their occurrence, g-NETs have been classified in a number of discussed ways into different grades that differ in their incidence and apparent pathogenesis. Based on a large amount of experimental data, tumorigenesis is mediated by gastrin’s effects on the CCK2R-receptor on ECL-cells that in turn leads to hyperplasia, dysplasia, and finally neoplasia. However, in all three conditions, the extent of response of ECL-cells to gastrin is modified by a number of genetic influences and other underlying risk factors, and by the duration of exposure to the hormonal influence. Data relating to trophic effects of hypergastrinemia due to PPI use in humans are reviewed and, in an attached Appendix A, all 11 reports of g-NETs that occurred in long-term PPI users in the absence of CAG or ZES are summarized. Mention of additional suspected cases reported elsewhere are also listed. Furthermore, the risk in humans may be affected by the presence of underlying conditions or genetic factors, including their PPI-metabolizer phenotype, with slow metabolizers likely at increased risk. Other problems in estimating the true incidence of g-NETs are discussed, relating to non-reporting of small tumors and failure of the Surveillance, Epidemiology, and End Results Program (SEER) and other databases, to capture small tumors or those not accorded a T1 rating. Overall, it appears likely that the true incidence of g-NETs may be seriously underestimated: the possibility that hypergastrinemia also affects tumorigenesis in additional gastrointestinal sites or in tumors in other organ systems is briefly examined. Overall, the risk of developing a g-NET appears greatest in patients who are more than 10 years on drug and on higher doses: those affected by chronic H. pylori gastritis and/or consequent gastric atrophy may also be at increased risk. While the overall risk of g-NETs induced by PPI therapy is undoubtedly low, it is real: this necessitates caution in using PPI therapy for long periods of time, particularly when initiated in young subjects.

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Gerard, Robert V., David B. MacLean, Romolo Fagianni, and Colin J. Lock. "Fastigiatine, a lycopodium alkaloid with a new ring system." Canadian Journal of Chemistry 64, no. 5 (May 1, 1986): 943–49. http://dx.doi.org/10.1139/v86-157.

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Fastigiatine, C19H28N2O, is a minor component of the alkaloids of Lycopodiumfastigiatum R•Br•collected in New Zealand. Its structure and relative configuration have been resolved by an X-ray analysis of the free base. The pentacyclic ring system of fastigiatine has not been previously observed in the Lycopodium family of alkaloids or elsewhere. A proposal is presented for its derivation from the tetracyclic flabellidane ring system that is widely distributed among Lycopodium species. The mass spectrum and the 13C and 1H nmr spectra of fastigiatine are discussed.

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Graulich, N., and G. Bhattacharyya. "Investigating students' similarity judgments in organic chemistry." Chemistry Education Research and Practice 18, no. 4 (2017): 774–84. http://dx.doi.org/10.1039/c7rp00055c.

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Organic chemistry is possibly the most visual science of all chemistry disciplines. The process of scientific inquiry in organic chemistry relies on external representations, such as Lewis structures, mechanisms, and electron arrows. Information about chemical properties or driving forces of mechanistic steps is not available through direct perception, and thus looking beyond the respresentation is challenging for learners. In this study, we investigated the categorization behavior of undergraduate students enrolled in an organic chemistry course when engaged in various categorization tasks involving electrophilic addition reactions to alkenes. The critical attribute a student chose to make a category out of a set of reactions was classified as perceptual or relational and gave insights into how students process and store information about reactions at an early level of expertise. Our results support the notion that students are prone to the surface level of representations and make sense of reactions depicted in a very minimalistic fashion. Implications for approaching this phenomenon in teaching are discussed.

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Vanhove, S., H. J. Lee, M. Beghyn, D. Van Gansbeke, S. Brockington, and M. Vincx. "The Metazoan Meiofauna in Its Biogeochemical Environment: The Case of an Antarctic Coastal Sediment." Journal of the Marine Biological Association of the United Kingdom 78, no. 2 (May 1998): 411–34. http://dx.doi.org/10.1017/s0025315400041539.

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The metazoan meiobenthos was investigated in an Antarctic coastal sediment (Factory Cove, Signy Island, Antarctica). The fine sands contained much higher abundances compared to major sublittoral sediments worldwide. Classified second after Narrangansett Bay (North Atlantic) they reached numbers of 13 × 106ind m-2. The meiofauna was highly abundant in the surface layers, but densities decreased sharply below 2 cm. Vertical profiles mirrored steep gradients of microbiota, chloropigments and organic matter and were coincident with chemical stratification. Spatial patchiness manifested especially in the surface layer. Nematodes dominated (up to 90%), andAponema, Chromctdorita, Diplolaimella, Daptonema, MicrolaimusandNeochromadoraconstituted almost the entire community. Overall, the nematode fauna showed a strong similarity with fine sand communities elsewhere. The dominant trophic strategies were epistrarum and non-selective deposit feeding, but the applied classification for feeding guild structure of the nematodes of Factory Cove is discussed. High standing stock, low diversity and shallow depth distribution may have occurred because of the high nutritive (chlorophyll exceeded lOOOmgm-2and constituted almost 50% of the organic pool) and reductive character of the benthic environment. These observations must have originated from the substantial input of fresh organic matter from phytoplankton and microphytobenthic production, typical for an Antarctic coastal ecosystem during the austral summer.

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Wijaya, Karna. "MULTIFUNCTION OF LAYERED AND POROUS MATERIALS." Indonesian Journal of Chemistry 2, no. 3 (June 9, 2010): 142–54. http://dx.doi.org/10.22146/ijc.21909.

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In this review, two sort of materials i.e layered and porous materias which were studied by the author and coworkers intensively and extensively will be described. These materials generally can be classified into two groups, namely layered organic and inorganic materials and porous organic and inorganic materials. To the materials which classified in the first group, it will be discussed the syntheses, characterization and application of layered organic materials of imidazolium-dimesylamidate and of layered inorganic materials of montmorillonite. For the second group, as examples we will analogically describe the syntheses, characterization and application of 2,6-dimethylpyridinium-di(methanesulfonyl)amidate porous organic material and zeolite and pillared clay porous inorganic materials. Keywords: layered materials, porous materials, syntheses, characterization, application.

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Weingart, Eric, Sarah Tschirner, Linda Teevs, and Ulf Prüße. "Conversion of Fructose to HMF in a Continuous Fixed Bed Reactor with Outstanding Selectivity." Molecules 23, no. 7 (July 20, 2018): 1802. http://dx.doi.org/10.3390/molecules23071802.

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5-Hydroxymethylfurfural (HMF) is a very promising component for bio-based plastics. Efficient synthesis of HMF from biomass is still challenging because of fast degradation of HMF to by-products under formation conditions. Therefore, different studies, conducted mainly in monophasic and biphasic batch systems with and without water addition have been published and are still under investigation. However, to produce HMF at a large scale, a continuous process is preferable. Until now, only a few studies have been published in this context. In this work, it is shown that fluorous alcohol hexafluoroisopropanol (HFIP) can act as superior reaction solvent for HMF synthesis from fructose in a fixed bed reactor. Very high yields of 76% HMF can be achieved in this system under optimized conditions, whilst the catalyst is very stable over several days. Such high yields are only described elsewhere with high boiling reaction solvents like dimethylsulfoxide (DMSO), whereas HFIP with a boiling point of 58 °C is very easy to separate from HMF.

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7

Grothe, Eline, Hugo Meekes, and René de Gelder. "Chirality and stereoisomerism of organic multicomponent crystals in the CSD." CrystEngComm 22, no. 43 (2020): 7380–88. http://dx.doi.org/10.1039/d0ce00403k.

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Shi, Yi-Zhong, Hao Wu, Kai Wang, Jia Yu, Xue-Mei Ou, and Xiao-Hong Zhang. "Recent progress in thermally activated delayed fluorescence emitters for nondoped organic light-emitting diodes." Chemical Science 13, no. 13 (2022): 3625–51. http://dx.doi.org/10.1039/d1sc07180g.

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The mechanism, exciton leaking channels, and reported molecular design strategies of TADF emitters for high-performance nondoped OLEDs are summarized. Their molecular structures depending on the functional A groups are further classified.

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Jing, Jingyun, and Congling Shi. "Reusable Magnetic Nanoparticle Immobilized Nitrogen-Containing Ligand for Classified and Easy Recovery of Heavy Metal Ions." Molecules 25, no. 14 (July 14, 2020): 3204. http://dx.doi.org/10.3390/molecules25143204.

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Functionalized Tris[2-(dimethylamino) ethyl] amine (Me6TREN) ligands tethered-Fe3O4@Me6TREN nanoparticles (NPs) with a size of 150 nm were prepared to achieve classified and easy recovery of heavy metal ions in wastewater. The preparation of such NPs related to sequential silane ligand exchange and a following cure and Schiff base reactions for Fe3O4 NPs. Fe3O4@Me6TREN NPs as an effective nano-adsorbent of heavy metals exhibited significant differences in maximum adsorption capacity for Cr(III) (61.4 mg/g), Cu(II) (245.0 mg/g), Pb(II) (5.3 mg/g), and Cd(II) (1136.2 mg/g), in favor of classified removal of heavy metals from wastewater. Furthermore, Fe3O4@Me6TREN NPs can be regenerated by desorbing metal ions from NP surfaces eluted with ethylenediaminetetraacetic acid disodium salt (EDTA-Na2) aqueous, which endows such NPs promising potency as new nano-vectors for the removal of heavy metals.

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10

Bryan, Tracy M. "G-Quadruplexes at Telomeres: Friend or Foe?" Molecules 25, no. 16 (August 13, 2020): 3686. http://dx.doi.org/10.3390/molecules25163686.

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Telomeres are DNA-protein complexes that cap and protect the ends of linear chromosomes. In almost all species, telomeric DNA has a G/C strand bias, and the short tandem repeats of the G-rich strand have the capacity to form into secondary structures in vitro, such as four-stranded G-quadruplexes. This has long prompted speculation that G-quadruplexes play a positive role in telomere biology, resulting in selection for G-rich tandem telomere repeats during evolution. There is some evidence that G-quadruplexes at telomeres may play a protective capping role, at least in yeast, and that they may positively affect telomere maintenance by either the enzyme telomerase or by recombination-based mechanisms. On the other hand, G-quadruplex formation in telomeric DNA, as elsewhere in the genome, can form an impediment to DNA replication and a source of genome instability. This review summarizes recent evidence for the in vivo existence of G-quadruplexes at telomeres, with a focus on human telomeres, and highlights some of the many unanswered questions regarding the location, form, and functions of these structures.

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González-Sálamo, Javier, Gabriel Jiménez-Skrzypek, Cecilia Ortega-Zamora, Miguel Ángel González-Curbelo, and Javier Hernández-Borges. "Covalent Organic Frameworks in Sample Preparation." Molecules 25, no. 14 (July 20, 2020): 3288. http://dx.doi.org/10.3390/molecules25143288.

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Covalent organic frameworks (COFs) can be classified as emerging porous crystalline polymers with extremely high porosity and surface area size, and good thermal stability. These properties have awakened the interests of many areas, opening new horizons of research and applications. In the Analytical Chemistry field, COFs have found an important application in sample preparation approaches since their inherent properties clearly match, in a good number of cases, with the ideal characteristics of any extraction or clean-up sorbent. The review article is meant to provide a detailed overview of the different COFs that have been used up to now for sample preparation (i.e., solid-phase extraction in its most relevant operational modes—conventional, dispersive, magnetic/solid-phase microextraction and stir-bar sorptive extraction); the extraction devices/formats in which they have been applied; and their performances and suitability for this task.

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12

Jiang, Haiyan, Jiahua He, Changyi Deng, Xiaodong Hong, and Bing Liang. "Advances in Bi2WO6-Based Photocatalysts for Degradation of Organic Pollutants." Molecules 27, no. 24 (December 8, 2022): 8698. http://dx.doi.org/10.3390/molecules27248698.

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With the rapid development of modern industries, water pollution has become an urgent problem that endangers the health of human and wild animals. The photocatalysis technique is considered an environmentally friendly strategy for removing organic pollutants in wastewater. As an important member of Bi-series semiconductors, Bi2WO6 is widely used for fabricating high-performance photocatalysts. In this review, the recent advances of Bi2WO6-based photocatalysts are summarized. First, the controllable synthesis, surface modification and heteroatom doping of Bi2WO6 are introduced. In the respect of Bi2WO6-based composites, existing Bi2WO6-containing binary composites are classified into six types, including Bi2WO6/carbon or MOF composite, Bi2WO6/g-C3N4 composite, Bi2WO6/metal oxides composite, Bi2WO6/metal sulfides composite, Bi2WO6/Bi-series composite, and Bi2WO6/metal tungstates composite. Bi2WO6-based ternary composites are classified into four types, including Bi2WO6/g-C3N4/X, Bi2WO6/carbon/X, Bi2WO6/Au or Ag-based materials/X, and Bi2WO6/Bi-series semiconductors/X. The design, microstructure, and photocatalytic performance of Bi2WO6-based binary and ternary composites are highlighted. Finally, aimed at the existing problems in Bi2WO6-based photocatalysts, some solutions and promising research trends are proposed that would provide theoretical and practical guidelines for developing high-performance Bi2WO6-based photocatalysts.

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13

Kulkarni, Sudhir A., and Shridhar R. Gadre. "On the Topography of Electron Momentum Densities of Linear Molecules." Zeitschrift für Naturforschung A 48, no. 1-2 (February 1, 1993): 145–50. http://dx.doi.org/10.1515/zna-1993-1-233.

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Abstract A topographical study of the electron momentum density (EMD) of some linear molecules is presented with special emphasis on the bond-directionality principle. A new approach to the bond-directionality (BD) principle has been proposed. This is based on the analysis of curvatures of critical points at p = 0 and elsewhere on the bonding axis. The linear molecules are classified into three broad categories: those which fully obey or disobey the BD principle as well as those which satisfy it only partly. The Laplacian of the EMD at p = 0 has been associated with the quality of the wavefunction via the electron density in the tail region. Also, the similarity in the critical structure of both the EMD and the spherically averaged EMD at the origin is brought out.

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Inglett, George E., and Diejun Chen. "Antioxidant Activity and Phenolic Content of Air-Classified Corn Bran." Cereal Chemistry Journal 88, no. 1 (January 2011): 36–40. http://dx.doi.org/10.1094/cchem-07-10-0104.

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15

Krylov, Igor B., Stanislav A. Paveliev, Alexander S. Budnikov, and Alexander O. Terent’ev. "Oxime radicals: generation, properties and application in organic synthesis." Beilstein Journal of Organic Chemistry 16 (June 5, 2020): 1234–76. http://dx.doi.org/10.3762/bjoc.16.107.

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N-Oxyl radicals (compounds with an N–O• fragment) represent one of the richest families of stable and persistent organic radicals with applications ranging from catalysis of selective oxidation processes and mechanistic studies to production of polymers, energy storage, magnetic materials design and spectroscopic studies of biological objects. Compared to other N-oxyl radicals, oxime radicals (or iminoxyl radicals) have been underestimated for a long time as useful intermediates for organic synthesis, despite the fact that their precursors, oximes, are extremely widespread and easily available organic compounds. Furthermore, oxime radicals are structurally exceptional. In these radicals, the N–O• fragment is connected to an organic moiety by a double bond, whereas all other classes of N-oxyl radicals contain an R2N–O• fragment with two single C–N bonds. Although oxime radicals have been known since 1964, their broad synthetic potential was not recognized until the last decade, when numerous selective reactions of oxidative cyclization, functionalization, and coupling mediated by iminoxyl radicals were discovered. This review is focused on the synthetic methods based on iminoxyl radicals developed in the last ten years and also contains some selected data on previous works regarding generation, structure, stability, and spectral properties of these N-oxyl radicals. The reactions of oxime radicals are classified into intermolecular (oxidation by oxime radicals, oxidative C–O coupling) and intramolecular. The majority of works are devoted to intramolecular reactions of oxime radicals. These reactions are classified into cyclizations involving C–H bond cleavage and cyclizations involving a double C=C bond cleavage.

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Banert, Klaus, and Jennifer Seifert. "Steric hindrance classified: treatment of isothiocyanatoallene with secondary amines bearing bulky substituents to generate 2-aminothiazoles." Organic Chemistry Frontiers 6, no. 20 (2019): 3517–22. http://dx.doi.org/10.1039/c9qo00312f.

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17

Roscoe, John M. "The kinetics of gas phase reactions studied in a "homogeneous reactor"." Canadian Journal of Chemistry 66, no. 9 (September 1, 1988): 2325–34. http://dx.doi.org/10.1139/v88-368.

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The use of a "well-stirred" or "homogeneous" reactor in kinetic studies of gas phase reactions has been examined to assess the sensitivity of the method to the criteria upon which its use is based. The effects of heterogeneous and homogeneous secondary reactions are considered and the validity of the assumption of homogeneity has been examined experimentally for conditions similar to those which have been used elsewhere. The atom sink presented by the excess reagent under pseudo first order conditions results in failure of the homogeneity assumption. However, it is found that homogeneity is not required for successful use of the method provided the analytical measurements have good spatial resolution and the reaction volume is well-defined. The method is illustrated by using it to study some reactions of O(3P).

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Daniels, R. Scott, Donald C. Wigfield, and Kenneth S. Williams. "Mathematical modelling of atom loss in delivery tubing." Canadian Journal of Chemistry 70, no. 7 (July 1, 1992): 1978–84. http://dx.doi.org/10.1139/v92-248.

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A mathematical model is presented to establish a relationship between the quantity of trace analyte vapor lost to the surface of delivery tubing and the tubing diameter, while in transit between stages of an instrument. Cold-vapor atomic absorption spectrometry for mercury, hydride generation techniques, and interfaces like the interface between electrothermal vaporization and inductively coupled plasma mass spectrometry all risk significant analyte loss before measurement. The results of this modelling substantiate the results of limited experimental work published elsewhere suggesting the use of the smallest possible tubing diameter for the delivery of atomic vapor through a tube. This diameter is calculable using Poiseuille's formula. Using this model, kinetic theory, and experimental data, the sticking probability for mercury on latex tubing is calculated to be approximately 1.6 × 10−6.

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Yang, Yuting, Changzheng Tu, Hongju Yin, Jianjun Liu, Feixiang Cheng, and Feng Luo. "Molecular Iodine Capture by Covalent Organic Frameworks." Molecules 27, no. 24 (December 19, 2022): 9045. http://dx.doi.org/10.3390/molecules27249045.

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The effective capture and storage of volatile molecular iodine from nuclear waste is of great significance. Covalent organic frameworks (COFs) are a class of extended crystalline porous polymers that possess unique architectures with high surface areas, long-range order, and permanent porosity. Substantial efforts have been devoted to the design and synthesis of COF materials for the capture of radioactive iodine. In this review, we first introduce research techniques for determining the mechanism of iodine capture by COF materials. Then, the influencing factors of iodine capture performance are classified, and the design principles and strategies for constructing COFs with potential for iodine capture are summarized on this basis. Finally, our personal insights on remaining challenges and future trends are outlined, in order to bring more inspiration to this hot topic of research.

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20

Bortolami, Martina, Isabella Chiarotto, Leonardo Mattiello, Rita Petrucci, Daniele Rocco, Fabrizio Vetica, and Marta Feroci. "Organic electrochemistry: Synthesis and functionalization of β-lactams in the twenty-first century." Heterocyclic Communications 27, no. 1 (January 1, 2021): 32–44. http://dx.doi.org/10.1515/hc-2020-0121.

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Abstract Organic electrochemistry is a technique that allows for the heterogeneous redox reactions avoiding both the use of stoichiometric amounts of redox reagents and the resulting formation of stoichiometric by-products. In fact, the redox reagent in these reactions is the electron, which is naturally eco-friendly and produces no side compounds. It is therefore quite obvious that electrochemistry can be classified as a “green” technology. The use of this methodology in the synthesis of β-lactams is not a novelty, but the growing interest in this class of biologically active compounds, due to the discovery of new fields of application (after a moment of decrease in interest due to antibiotic resistance) has been a stimulus for the search for more efficient electrochemical ways to synthesize and transform β-lactams. Thus, this review deals with the twenty-first-century applications of electroorganic technique to the chemistry of β-lactams, by analyzing first the syntheses classified by the type of reactions (cyclization, cycloaddition, etc.) and then by manipulating the β-lactam structure, using it as a synthon. Lastly, the importance of this technique is demonstrated by a study of a pilot plant scale reduction of a cephalosporanic acid derivative to a commercially important antibiotic.

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Razali, Muhammad, Zaim Zainal, M. Maulidiani, Khozirah Shaari, Zulkifli Zamri, Mohd Mohd Idrus, Alfi Khatib, et al. "Classification of Raw Stingless Bee Honeys by Bee Species Origins Using the NMR- and LC-MS-Based Metabolomics Approach." Molecules 23, no. 9 (August 28, 2018): 2160. http://dx.doi.org/10.3390/molecules23092160.

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The official standard for quality control of honey is currently based on physicochemical properties. However, this method is time-consuming, cost intensive, and does not lead to information on the originality of honey. This study aims to classify raw stingless bee honeys by bee species origins as a potential classifier using the NMR-LCMS-based metabolomics approach. Raw stingless bee honeys were analysed and classified by bee species origins using proton nuclear magnetic resonance (1H-NMR) spectroscopy and an ultra-high performance liquid chromatography-quadrupole time of flight mass spectrometry (UHPLC-QTOF MS) in combination with chemometrics tools. The honey samples were able to be classified into three different groups based on the bee species origins of Heterotrigona itama, Geniotrigona thoracica, and Tetrigona apicalis. d-Fructofuranose (H. itama honey), β-d-Glucose, d-Xylose, α-d-Glucose (G. thoracica honey), and l-Lactic acid, Acetic acid, l-Alanine (T. apicalis honey) ident d-Fructofuranose identified via 1H-NMR data and the diagnostic ions of UHPLC-QTOF MS were characterized as the discriminant metabolites or putative chemical markers. It could be suggested that the quality of honey in terms of originality and purity can be rapidly determined using the classification technique by bee species origins via the 1H-NMR- and UHPLC-QTOF MS-based metabolomics approach.

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Hao, Yuanqiang, Qianye Yin, Yintang Zhang, Maotian Xu, and Shu Chen. "Recent Progress in the Development of Fluorescent Probes for Thiophenol." Molecules 24, no. 20 (October 16, 2019): 3716. http://dx.doi.org/10.3390/molecules24203716.

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Thiophenol (PhSH) belongs to a class of highly reactive and toxic aromatic thiols with widespread applications in the chemical industry for preparing pesticides, polymers, and pharmaceuticals. In this review, we comprehensively summarize recent progress in the development of fluorescent probes for detecting and imaging PhSH. These probes are classified according to recognition moieties and are detailed on the basis of their structures and sensing performances. In addition, prospects for future research are also discussed.

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Rezvani Ghomi, Erfan, Fatemeh Khosravi, Zahra Mossayebi, Ali Saedi Ardahaei, Fatemeh Morshedi Dehaghi, Masoud Khorasani, Rasoul Esmaeely Neisiany, et al. "The Flame Retardancy of Polyethylene Composites: From Fundamental Concepts to Nanocomposites." Molecules 25, no. 21 (November 5, 2020): 5157. http://dx.doi.org/10.3390/molecules25215157.

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Polyethylene (PE) is one the most used plastics worldwide for a wide range of applications due to its good mechanical and chemical resistance, low density, cost efficiency, ease of processability, non-reactivity, low toxicity, good electric insulation, and good functionality. However, its high flammability and rapid flame spread pose dangers for certain applications. Therefore, different flame-retardant (FR) additives are incorporated into PE to increase its flame retardancy. In this review article, research papers from the past 10 years on the flame retardancy of PE systems are comprehensively reviewed and classified based on the additive sources. The FR additives are classified in well-known FR families, including phosphorous, melamine, nitrogen, inorganic hydroxides, boron, and silicon. The mechanism of fire retardance in each family is pinpointed. In addition to the efficiency of each FR in increasing the flame retardancy, its impact on the mechanical properties of the PE system is also discussed. Most of the FRs can decrease the heat release rate (HRR) of the PE products and simultaneously maintains the mechanical properties in appropriate ratios. Based on the literature, inorganic hydroxide seems to be used more in PE systems compared to other families. Finally, the role of nanotechnology for more efficient FR-PE systems is discussed and recommendations are given on implementing strategies that could help incorporate flame retardancy in the circular economy model.

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Okayasu, T., and K. Sorimachi. "Organisms can essentially be classified according to two codon patterns." Amino Acids 36, no. 2 (April 1, 2008): 261–71. http://dx.doi.org/10.1007/s00726-008-0059-0.

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Barta, Petra, Ferenc Fülöp, and István Szatmári. "Mannich base-connected syntheses mediated by ortho-quinone methides." Beilstein Journal of Organic Chemistry 14 (March 6, 2018): 560–75. http://dx.doi.org/10.3762/bjoc.14.43.

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This article provides an overview about specifically modified Mannich reactions where the process involves an ortho-quinone methide (o-QM) intermediate. The reactions are classified on the basis of the o-QM source followed by the reactant, e.g., the dienophile partner in cycloaddition reactions (C=C or C=N dienophiles) or by the formation of multicomponent Mannich adducts. Due to the important pharmacological activities of these reactive o-QM intermediates, special attention is paid to the biological activity of these compounds.

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Medici, Fabrizio, Simonetta Resta, Alessandra Puglisi, Sergio Rossi, Laura Raimondi, and Maurizio Benaglia. "Electrochemical Organic Synthesis of Electron-Rich Biaryl Scaffolds: An Update." Molecules 26, no. 22 (November 18, 2021): 6968. http://dx.doi.org/10.3390/molecules26226968.

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Biaryl scaffolds are widely spread in biologically important natural products, in numerous therapeutic agents, but they are also considered a privileged class of ligands and (organo)catalysts; therefore, the development of efficient alternative methodologies to prepare such compounds is always attracting much attention. The present review discusses the organic electrosynthesis of biaryls starting from phenols, anilines, naphthols, and naphthylamines. The most significant examples of the works reported in the last decade are presented and classified according to the single class of molecules: after the introduction, the first three sections relate to the reactions of phenols, naphthols, and anilines, respectively; the other two sections refer to cross-coupling and miscellaneous reactions.

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Foretić, Blaženka, Vladimir Damjanović, Robert Vianello, and Igor Picek. "Novel Insights into the Thioesterolytic Activity of N-Substituted Pyridinium-4-oximes." Molecules 25, no. 10 (May 21, 2020): 2385. http://dx.doi.org/10.3390/molecules25102385.

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The pyridinium oximes are known esterolytic agents, usually classified in the literature as catalysts, which mimic the catalytic mode of hydrolases. Herein, we combined kinetic and computational studies of the pyridinium-4-oxime-mediated acetylthiocholine (AcSCh+) hydrolysis to provide novel insights into their potential catalytic activity. The N-methyl- and N-benzylpyridinium-4-oximes have been tested as oximolytic agents toward the AcSCh+, while the newly synthesized O-acetyl-N-methylpyridinium-4-oxime iodide was employed for studying the consecutive hydrolytic reaction. The relevance of the AcSCh+ hydrolysis as a competitive reaction to AcSCh+ oximolysis was also investigated. The reactions were independently studied spectrophotometrically and rate constants, koxime, kw and kOH, were evaluated over a convenient pH-range at I = 0.1 M and 25 °C. The catalytic action of pyridinium-4-oximes comprises two successive stages, acetylation (oximolysis) and deacetylation stage (pyridinium-4-oxime-ester hydrolysis), the latter being crucial for understanding the whole catalytic cycle. The complete mechanism is presented by the free energy reaction profiles obtained with (CPCM)/M06–2X/6–311++G(2df,2pd)//(CPCM)/M06–2X/6–31+G(d) computational model. The comparison of the observed rates of AcSCh+ oximolytic cleavage and both competitive AcSCh+ and consecutive pyridinium-4-oxime-ester hydrolytic cleavage revealed that the pyridinium-4-oximes cannot be classified as non-enzyme catalyst of the AcSCh+ hydrolysis but as the very effective esterolytic agents.

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Klančar, A., M. Zakotnik, R. Roškar, and J. Trontelj. "Multi-residue analysis of selected pharmaceuticals in wastewater samples by stir-bar sorptive extraction followed by liquid desorption and liquid chromatography-mass spectrometry." Analytical Methods 9, no. 36 (2017): 5310–21. http://dx.doi.org/10.1039/c7ay01310h.

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Cammerata, Alessandro, Rosita Marabottini, Enrica Allevato, Gabriella Aureli, and Silvia Rita Stazi. "Content of minerals and deoxynivalenol in the air‐classified fractions of durum wheat." Cereal Chemistry 98, no. 5 (June 22, 2021): 1101–11. http://dx.doi.org/10.1002/cche.10458.

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30

Qiu, Yi, Wen-Jian Lan, Hou-Jin Li, and Liu-Ping Chen. "Linear Triquinane Sesquiterpenoids: Their Isolation, Structures, Biological Activities, and Chemical Synthesis." Molecules 23, no. 9 (August 21, 2018): 2095. http://dx.doi.org/10.3390/molecules23092095.

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Linear triquinane sesquiterpenoids represent an important class of natural products. Most of these compounds were isolated from fungi, sponges, and soft corals, and many of them displayed a wide range of biological activities. On account of their structural diversity and complexity, linear triquinane sesquiterpenoids present new challenges for chemical structure identification and total synthesis. 118 linear triquinane sesquiterpenoids were classified into 8 types, named types I–VIII, based on the carbon skeleton and the position of carbon substituents. Their isolation, structure elucidations, biological activities, and chemical synthesis were reviewed. This paper cited 102 articles from 1947 to 2018.

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31

Wagner, Justine, Yunjia Song, Jenna Shapiro, and Howard E. Katz. "Oxygen-bearing functionalities enhancing NO₂, NH₃, and acetone electronic response and response variation by polythiophenes in organic field-effect transistor sensors." Journal of Materials Chemistry C 10, no. 6 (2022): 2149–62. http://dx.doi.org/10.1039/d1tc04650k.

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Thiophene copolymers (representative structures shown) gave enhanced, uncorrelated response to NO2, NH3, and acetone vapors. Linear discriminant analysis of responses of thirteen polymers correctly classified response groups as arising from individual vapors.

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32

Varsadiya, Milan, Tim Urich, Gustaf Hugelius, and Jiří Bárta. "Fungi in Permafrost-Affected Soils of the Canadian Arctic: Horizon- and Site-Specific Keystone Taxa Revealed by Co-Occurrence Network." Microorganisms 9, no. 9 (September 13, 2021): 1943. http://dx.doi.org/10.3390/microorganisms9091943.

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Permafrost-affected soil stores a significant amount of organic carbon. Identifying the biological constraints of soil organic matter transformation, e.g., the interaction of major soil microbial soil organic matter decomposers, is crucial for predicting carbon vulnerability in permafrost-affected soil. Fungi are important players in the decomposition of soil organic matter and often interact in various mutualistic relationships during this process. We investigated four different soil horizon types (including specific horizons of cryoturbated soil organic matter (cryoOM)) across different types of permafrost-affected soil in the Western Canadian Arctic, determined the composition of fungal communities by sequencing (Illumina MPS) the fungal internal transcribed spacer region, assigned fungal lifestyles, and by determining the co-occurrence of fungal network properties, identified the topological role of keystone fungal taxa. Compositional analysis revealed a significantly higher relative proportion of the litter saprotroph Lachnum and root-associated saprotroph Phialocephala in the topsoil and the ectomycorrhizal close-contact exploring Russula in cryoOM, whereas Sites 1 and 2 had a significantly higher mean proportion of plant pathogens and lichenized trophic modes. Co-occurrence network analysis revealed the lowest modularity and average path length, and highest clustering coefficient in cryoOM, which suggested a lower network resistance to environmental perturbation. Zi-Pi plot analysis suggested that some keystone taxa changed their role from generalist to specialist, depending on the specific horizon concerned, Cladophialophora in topsoil, saprotrophic Mortierella in cryoOM, and Penicillium in subsoil were classified as generalists for the respective horizons but specialists elsewhere. The litter saprotrophic taxon Cadophora finlandica played a role as a generalist in Site 1 and specialist in the rest of the sites. Overall, these results suggested that fungal communities within cryoOM were more susceptible to environmental change and some taxa may shift their role, which may lead to changes in carbon storage in permafrost-affected soil.

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Li, Yangyan, Xiang Chen, Xiaoming Chen, and Xiao Shen. "Organophosphine-Catalyzed [4C+X] Annulations." Molecules 23, no. 11 (November 19, 2018): 3022. http://dx.doi.org/10.3390/molecules23113022.

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In recent years, there have been extraordinary developments of organophosphine-catalyzed reactions. This includes progress in the area of [4C+X] annulations, which are of particular interest due to their potential for the rapid construction of 5–8-membered cyclic products. In this short overview, we summarize the remarkable progress, emphasizing reaction mechanisms and key intermediates involved in the processes. The discussion is classified according to the type of electrophilic reactants that acted as C4 synthons in the annulation process, in the order of α-alkyl allenoates, γ-alkyl allenoates, α-methyl allene ketones, β′-OAc allenoate, δ-OAc allenoate, activated dienes and cyclobutenones.

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34

Román, Luz E., Enrique D. Gomez, José L. Solís, and Mónica M. Gómez. "Antibacterial Cotton Fabric Functionalized with Copper Oxide Nanoparticles." Molecules 25, no. 24 (December 9, 2020): 5802. http://dx.doi.org/10.3390/molecules25245802.

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Textiles functionalized with cupric oxide (CuO) nanoparticles have become a promising option to prevent the spread of diseases due to their antimicrobial properties, which strongly depend on the structure and morphology of the nanoparticles and the method used for the functionalization process. This article presents a review of work focused on textiles functionalized with CuO nanoparticles, which were classified into two groups, namely, in situ and ex situ. Moreover, the analyzed bacterial strains, the resistance of the antimicrobial properties of textiles to washing processes, and their cytotoxicity were identified. Finally, the possible antimicrobial mechanisms that could develop in Gram-positive and Gram-negative bacteria were described.

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35

Chen, Lingran, and Johann Gasteiger. "Organic Reactions Classified by Neural Networks: Michael Additions, Friedel–Crafts Alkylations by Alkenes, and Related Reactions." Angewandte Chemie International Edition in English 35, no. 7 (April 19, 1996): 763–65. http://dx.doi.org/10.1002/anie.199607631.

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36

Wang, Feiyan, Yongjing Huang, Wen Wu, Congyi Zhu, Ruimin Zhang, Jiezhong Chen, and Jiwu Zeng. "Metabolomics Analysis of the Peels of Different Colored Citrus Fruits (Citrus reticulata cv. ‘Shatangju’) During the Maturation Period Based on UHPLC-QQQ-MS." Molecules 25, no. 2 (January 17, 2020): 396. http://dx.doi.org/10.3390/molecules25020396.

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Citrus is a globally consumed fruit with great popularity. Mandarin (Citrus reticulata cv. ‘Shatangju’) is a local variety, and its planting area and yield are the greatest regarding fruit tree planting in Guangdong Province, China. However, its resistance to Huanglongbing (HLB) is weak. After infection by HLB, the fruits cannot develop normally. In this study, four kinds of fruits were classified as HBG, XQG, ZQG, and DHG, according to the color of their peels. The metabolomes of the three abnormally colored groups (HBG, XQG, and ZQG) and the normally colored group (DHG) were compared using a UPLC-QQQ-MS-based metabolomics approach. In total, 913 metabolites were identified and classified into 23 different categories, including phenylpropanoids and flavonoids; among them, 215 (HBG, 177; XQG, 124; and ZQG, 62) metabolites showed differential accumulation in the three comparison groups (HBG/XQG/ZQG versus DHG). A total of 2 unique metabolites, O-caffeoyl maltotriose and myricetin were detected only in DHG samples. When comparing HBG with DHG, there were 109 decreased and 68 increased metabolites; comparing XQG with DHG, there were 88 decreased and 36 increased metabolites; comparing ZQG with DHG, 41 metabolites were decreased, and 21 metabolites were increased. Metabolic pathway enrichment analysis of these differential metabolites showed significant enrichment of the “phenylpropanoid biosynthesis” pathway in all comparison groups. The hierarchical cluster analysis of the differential metabolites of the four groups showed a clear grouping patterns. The relative contents of three phenylpropanoids, four flavonoids, two alkaloids, one anthocyanin, and two other metabolites were significantly different between each comparison group. This study might provide fundamental insight for the isolation and identification of functional compounds from the peels of citrus fruit infected with HLB and for in-depth research on the effect of HLB on the formation of fruits pigment and the development of HLB-resistant citrus varieties.

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Sosulski, F. W., R. Hoover, R. T. Tyler, E. D. Murray, and S. D. Arntfield. "Differential Scanning Calorimetry of Air-Classified Starch and Protein Fractions from Eight Legume Species." Starch - Stärke 37, no. 8 (1985): 257–62. http://dx.doi.org/10.1002/star.19850370803.

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38

Chota, Alexander, Blassan P. George, and Heidi Abrahamse. "Potential Treatment of Breast and Lung Cancer Using Dicoma anomala, an African Medicinal Plant." Molecules 25, no. 19 (September 27, 2020): 4435. http://dx.doi.org/10.3390/molecules25194435.

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Globally, cancer has been identified as one of the leading causes of death in public health. Its etiology is based on consistent exposure to carcinogenic. Plant-derived anticancer compounds are known to be less toxic to the normal cells and are classified into acetylenic compounds, phenolics, terpenes, and phytosterols. Dicoma anomala is a perennial herb belonging to the family Asteraceae and is widely distributed in Sub-Saharan Africa and used in the treatment of cancer, malaria, fever, diabetes, ulcers, cold, and cough. This review aimed at highlighting the benefits of D. anomala in various therapeutic applications with special reference to the treatment of cancers and the mechanisms through which the plant-derived agents induce cell death.

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39

Li, Meijie, Feifei Hou, Tong Wu, Xinglin Jiang, Fuli Li, Haobao Liu, Mo Xian, and Haibo Zhang. "Recent advances of metabolic engineering strategies in natural isoprenoid production using cell factories." Natural Product Reports 37, no. 1 (2020): 80–99. http://dx.doi.org/10.1039/c9np00016j.

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40

MORRIS, D. "Physical Organic Chemistry 2nd ed.: Calvin D. Ritchie, Dekker, New York, 1990. Pages x + 357. $59.75 (U.S. and Canada), $71.50 (elsewhere)." Talanta 37, no. 11 (November 1990): ii. http://dx.doi.org/10.1016/0039-9140(90)80168-f.

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41

Mistri, Rajib. "Catalytic Organic Reactions in Liquid Phase by Perovskite Oxides: A Review." Asian Journal of Chemistry 34, no. 10 (2022): 2489–98. http://dx.doi.org/10.14233/ajchem.2022.23976.

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The structural flexibility and controllable physico-chemical characters of perovskite oxides have drawn major attention of researchers for catalytic reactions. Perovskite oxide are mainly used as catalysts for electrochemical, high temperature gas-phase and photocatalytic reactions but their uses for catalytic organic reactions in liquid phase are limited. Various porous and nano-perovskite oxides have been prepared by different methods are effectively used as catalyst for different types of organic reactions in liquid phase. The liquid-phase catalytic organic reactions over perovskite oxides have been classified mainly into three groups: (i) acid/base catalyzed, (ii) selective oxidation and (iii) cross-coupling reactions. This review article mainly emphases on different examples of perovskite oxides catalyzed organic reactions in liquid phase along with the relationships among the unique catalytic performance with the structural and the physico-chemical properties of perovskites.

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42

Mu, Ruipu, Zhaoshuai Wang, Max C. Wamsley, Colbee N. Duke, Payton H. Lii, Sarah E. Epley, London C. Todd, and Patty J. Roberts. "Application of Enzymes in Regioselective and Stereoselective Organic Reactions." Catalysts 10, no. 8 (July 24, 2020): 832. http://dx.doi.org/10.3390/catal10080832.

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Nowadays, biocatalysts have received much more attention in chemistry regarding their potential to enable high efficiency, high yield, and eco-friendly processes for a myriad of applications. Nature’s vast repository of catalysts has inspired synthetic chemists. Furthermore, the revolutionary technologies in bioengineering have provided the fast discovery and evolution of enzymes that empower chemical synthesis. This article attempts to deliver a comprehensive overview of the last two decades of investigation into enzymatic reactions and highlights the effective performance progress of bio-enzymes exploited in organic synthesis. Based on the types of enzymatic reactions and enzyme commission (E.C.) numbers, the enzymes discussed in the article are classified into oxidoreductases, transferases, hydrolases, and lyases. These applications should provide us with some insight into enzyme design strategies and molecular mechanisms.

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43

Mann, Stephen, Douglas D. Archibald, Jon M. Didymus, Brigid R. Heywood, Fiona C. Meldrum, and Vanessa J. Wade. "Biomineralization: Biomimetic Potential at the Inorganic-Organic Interface." MRS Bulletin 17, no. 10 (October 1992): 32–36. http://dx.doi.org/10.1557/s0883769400046455.

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The impetus for a biomimetic approach to mineralization stems from the need for increasingly sophisticated materials showing greater efficiency, specialization, and optimization—properties that ultimately depend on the control of molecular and supramolecular structure, and hence on methods of predictive chemical fabrication. Biomineralization is of central importance to the development of new approaches in materials science because, as discussed in the preceding article by Fink, the formation of bioinorganic materials, such as bones, shells, and teeth is highly regulated and responsive to the surrounding environment in a manner not achieved by conventional synthetic routes. Some possible areas of overlap are shown in Figure 1. As in the other areas of biomaterials discussed in this and next month's issue of the MRS Bulletin, there are two potential connections between the natural processes of biomineralization and the synthetic demands of materials science; first, the commercial exploitation of biologically derived, tailored materials, and second, the assimilation and adaptation of biological concepts and mechanisms into “artificial” materials design and synthesis. The former is an extension of biotechnology, by which microbial systems could be utilized to produce mineral powders. Some of the possible processes have been discussed elsewhere. In general, the use of biological sources is only applicable where the high production costs are offset by a marketable specialty product. While this is feasible for organic-based products such as polyhydroxybutyrate (see next month's MRS Bulletin) it imposes a severe limitation when we transfer the approach to biomineralization.

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Wang, Linqing, Haiyong Zhu, Tianyu Peng, and Dongxu Yang. "Conjugated ynones in catalytic enantioselective reactions." Organic & Biomolecular Chemistry 19, no. 10 (2021): 2110–45. http://dx.doi.org/10.1039/d0ob02521f.

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This review summarizes the recent literature examples of catalytic asymmetric reactions of conjugated ynones and classified these reaction types, alongside their mechanistic insights whenever possible.

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45

Stefaniak, Monika, and Jarosław Romański. "Facile Synthesis of Hydroxy-Substituted Thiacrown Ethers via Nucleophilic Ring Opening of Epoxides." Synthesis 51, no. 10 (February 25, 2019): 2214–20. http://dx.doi.org/10.1055/s-0037-1612249.

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The title thiacrown ethers were prepared in a one-step procedure to give a series of unique macrocycles possessing two unsubstituted hydroxy groups that can be easily functionalized. In addition, epoxides and macrocycles derived from Cookson’s birdcage diketone, were prepared. The nucleophilic ring opening of epoxides synthesis can be classified in the frame of click chemistry. Surprisingly, some of the prepared allyl substituted polyglycols as well as bis-epoxides, especially sulfur analogues, were prepared for the first time.

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46

Cigáň, Marek, Peter Danko, Henrich Brath, Matúš Čakurda, Roman Fišera, Jana Donovalová, Juraj Filo, et al. "4-Azafluorenone and α-Carboline Fluorophores with Green and Violet/Blue Emission." Molecules 24, no. 13 (June 27, 2019): 2378. http://dx.doi.org/10.3390/molecules24132378.

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The emission properties of three 4-azafluorenone and five new α-carboline fluorophores in both solution and thin solid films were investigated. Fluorescence of the azafluorenone is clearly enhanced in thin solid films due to the presence of phenyl/biphenyl rotors, and these derivatives can be classified as green Aggregation-Induced Emission luminogens (AIEgens) with a non-emissive heteroaromatic core structure. Compared to azafluorenones, emission of α-carbolines is hypsochromically shifted to the blue region of the electromagnetic spectrum, and most of these derivatives exhibit strong violet-blue fluorescence in both solution and thin solid film layers. Further, the effective mobility and electroluminescence of new α-carbolines were investigated in prepared organic field-effect transistors and organic light-emitting diodes, respectively.

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Toropov, Andrey A., and Alla P. Toropova. "QSPR/QSAR: State-of-Art, Weirdness, the Future." Molecules 25, no. 6 (March 12, 2020): 1292. http://dx.doi.org/10.3390/molecules25061292.

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Ability of quantitative structure–property/activity relationships (QSPRs/QSARs) to serve for epistemological processes in natural sciences is discussed. Some weirdness of QSPR/QSAR state-of-art is listed. There are some contradictions in the research results in this area. Sometimes, these should be classified as paradoxes or weirdness. These points are often ignored. Here, these are listed and briefly commented. In addition, hypotheses on the future evolution of the QSPR/QSAR theory and practice are suggested. In particular, the possibility of extending of the QSPR/QSAR problematic by searching for the “statistical similarity” of different endpoints is suggested and illustrated by an example for relatively “distanced each from other” endpoints, namely (i) mutagenicity, (ii) anticancer activity, and (iii) blood–brain barrier.

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Grabowski, Sławomir J. "Molecular Hydrogen as a Lewis Base in Hydrogen Bonds and Other Interactions." Molecules 25, no. 14 (July 20, 2020): 3294. http://dx.doi.org/10.3390/molecules25143294.

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The second-order Møller–Plesset perturbation theory calculations with the aug-cc-pVTZ basis set were performed for complexes of molecular hydrogen. These complexes are connected by various types of interactions, the hydrogen bonds and halogen bonds are most often represented in the sample of species analysed; most interactions can be classified as σ-hole and π-hole bonds. Different theoretical approaches were applied to describe these interactions: Quantum Theory of ‘Atoms in Molecules’, Natural Bond Orbital method, or the decomposition of the energy of interaction. The energetic, geometrical, and topological parameters are analysed and spectroscopic properties are discussed. The stretching frequency of the H-H bond of molecular hydrogen involved in intermolecular interactions is considered as a parameter expressing the strength of interaction.

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Bizzarri, Bruno Mattia, Raffaele Saladino, Ines Delfino, Juan Manuel García-Ruiz, and Ernesto Di Mauro. "Prebiotic Organic Chemistry of Formamide and the Origin of Life in Planetary Conditions: What We Know and What Is the Future." International Journal of Molecular Sciences 22, no. 2 (January 18, 2021): 917. http://dx.doi.org/10.3390/ijms22020917.

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The goal of prebiotic chemistry is the depiction of molecular evolution events preceding the emergence of life on Earth or elsewhere in the cosmos. Plausible experimental models require geochemical scenarios and robust chemistry. Today we know that the chemical and physical conditions for life to flourish on Earth were at work much earlier than thought, i.e., earlier than 4.4 billion years ago. In recent years, a geochemical model for the first five hundred million years of the history of our planet has been devised that would work as a cradle for life. Serpentinization processes in the Hadean eon affording self-assembled structures and vesicles provides the link between the catalytic properties of the inorganic environment and the impressive chemical potential of formamide to produce complete panels of organic molecules relevant in pre-genetic and pre-metabolic processes. Based on an interdisciplinary approach, we propose basic transformations connecting geochemistry to the chemistry of formamide, and we hint at the possible extension of this perspective to other worlds.

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Gu, Shu Fen, Xiao Hong Xiong, Le Le Gong, Hui Ping Zhang, Ying Xu, Xue Feng Feng, and Feng Luo. "Classified Encapsulation of an Organic Dye and Metal–Organic Complex in Different Molecular Compartments for White-Light Emission and Selective Adsorption of C2H2 over CO2." Inorganic Chemistry 60, no. 11 (May 21, 2021): 8211–17. http://dx.doi.org/10.1021/acs.inorgchem.1c00863.

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Journal articles on the topic 'Organic Chemistry not elsewhere classified'

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