Готові списки джерел за темами / Organic reductants

Добірка наукової літератури з теми "Organic reductants"

Автор: Grafiati
Опубліковано: 7 липня 2024

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Статті в журналах з теми "Organic reductants":

1

Irmeilyana, Irmeilyana, Ngudiantoro Ngudiantoro, Sri Indra Maiyanti, and Siddiq Makhalli. "LOGISTIC REGRESSION MODELING OF REDUCTANT HERBICIDE IN PAGARALAM COFFEE FARMING." BAREKENG: Jurnal Ilmu Matematika dan Terapan 17, no. 4 (December 18, 2023): 1957–68. http://dx.doi.org/10.30598/barekengvol17iss4pp1957-1968.

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The presence of weeds can affect the productivity of coffee plants. The use of herbicides that are not wise in controlling weeds can have a negative impact on the quality of coffee production and land. This study aims to obtain a binary logistic regression model of the use of reductant herbicides by coffee farmers in Pagaralam South Sumatera. This research involved 165 coffee farmers, consisting of 81 farmers who used reductants and 85 farmers who did not use reductants. In the results of bivariate analysis, variables that have a significant effect on the status of using reductant herbicides, do not necessarily have a significant effect on the logistic regression model. Overall prediction accuracy of the model results of the enter method and backward method are respectively 78.2% and 76.4%. The two best models obtained show that farmer age, number of trees, number of family workers, and land productivity can reduce the probability value of farmers using reductant herbicide. On the other hand, variables that can increase the opportunity value of using reductants, starting with the greatest effect, are net income, length of harvest, frequency of herbicide use, frequency of use of organic fertilizers, and age of trees. Based on the factors that affect the use of reductants, coffee farmers should set aside costs for land maintenance, including costs for environmentally friendly weed control, so that they can support the coffee plants to continue producing optimally.
2

Perez-Benito, Joaquin F., and Conchita Arias. "A kinetic study on the reactivity of chromium(IV)." Canadian Journal of Chemistry 71, no. 5 (May 1, 1993): 649–55. http://dx.doi.org/10.1139/v93-087.

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The inhibition effect of Mn2+ on the rates of the Cr(VI) oxidations of 13 different organic reductants (RH) in aqueous perchloric acid has been studied. The reductants were formaldehyde, formic acid, maleic acid, and 10 alcohols (8 primary and 2 secondary). The second-order rate constants decrease with increasing [Mn2+] according to the law[Formula: see text]Parameter b′ is interpreted as the ratio between the rate constants for the Cr(IV)–Mn2+ and Cr(IV)–RH reactions. Cr(IV) is reduced by Mn2+ (and also by Ce3+) much faster than by organic reductants RH. The Cr(IV) oxidations of primary alcohols follow Taft's equation with a negative reaction constant (ρ* = −0.80 ± 0.06). The Cr(IV) present in aqueous perchloric acid is postulated as an oxo species (CrO2+) capable of reacting by one-electron transfer with both Mn2+ and Ce3+, and by hydride-ion transfer with organic reductants. Relevance of these results to the general mechanism for the Cr(VI) oxidations of organic substrates is discussed.
3

Mukhammadiev, Komil, Dilrabo Mukhammadieva, Akhan Demeuov, and Inoyatkhan Tuichyeva. "Disposal of highly toxic waste chromium solutions." E3S Web of Conferences 531 (2024): 04010. http://dx.doi.org/10.1051/e3sconf/202453104010.

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The aim of the study is to determine the effect of organic reductants (sawdust) on the degree of reduction of chromium (VI) ions in the complex processing of waste chromium-containing solution (electrolyte) of plating production, as at the same time to determine the optimum conditions of the process. Experimental results showed that organic reductants (sawdust, and lignin) in an acid environment work as a reagent-reductant of chromium (VI) ions. The process of reduction of chromium (VI) ions to chromium (III) proceeds intensively for the first 20-30 min and is completed within 50 minutes, while about 1.0-2.5% of chromium (VI) ions remain unreduced, and 97.0-99.0% of chromium (VI) ions of the total amount pass into trivalent form. Chromium (VI) ions are reduced at the first stage of the process, the bulk of them are converted into chromium (III) ions and emitted as chromium (III) hydroxide, and wastewater is further purified at the second stage. When using lignin, the reduction in the concentration of chromium (VI) ions is insignificant, since the number of active functional groups in its structure is limited. Model studies presented in this work and their approbation on production wastewater showed expediency and sufficiently high efficiency of using woodworking wastes (sawdust) to reduce chromium (VI) ions from the spent solutions. Sawdust consists mainly of cellulose; its structure contains functional groups that act as a reductant during oxidation. Further study of the process mechanism and characteristics is essential for the development of recommendations for their utilization.
4

Kipp, Brian H., Chadi Faraj, Guoliang Li, and David Njus. "Imidazole facilitates electron transfer from organic reductants." Bioelectrochemistry 64, no. 1 (August 2004): 7–13. http://dx.doi.org/10.1016/j.bioelechem.2003.12.010.

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5

Irmeilyana, Irmeilyana, Ngudiantoro Ngudiantoro, Sri Indra Maiyanti, and Indrike Febriyanti. "Correspondence Analysis to Know Factors Related to the Use of Reducant Herbicide on Pagaralam Coffee Farmers." Pattimura International Journal of Mathematics (PIJMath) 1, no. 2 (November 1, 2022): 69–80. http://dx.doi.org/10.30598/pijmathvol1iss2pp69-80.

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Weed control is an attempt to care for agricultural land that can affect coffee production. This study aims to analyze the factors that have a relationship with the use of reductant herbicide in Pagaralam coffee farmers by using simple correspondence analysis. The research data included 19 variables and 3 categories of respondents based on the use of reductant herbicide, namely non-users, new users, and users. At the initial stage, each variable was carried out a mean difference test between 2 categories of respondents. Furthermore, each variable is divided into several categories. Then, by using the independence test, the categories of each variable are associated with the category of reductant use. There are 7 factors that have a relationship with the use of reductants, namely education of respondents, age of trees, length of harvest, frequency of herbicide use, frequency of chemical fertilizers used, frequency of organic fertilizers used, and number of labour outside the family (TL). The results of the correspondence analysis plot can show differences in the characteristics of the respondent's categories according to the use of reductant herbicide. The user category is dominantly characterized by having junior high school education, tree age more than 25 years, tend not to use organic fertilizer, and the harvest period can reach 3 months.
6

Beagan, Daniel M., Veronica Carta, and Kenneth G. Caulton. "A reagent for heteroatom borylation, including iron mediated reductive deoxygenation of nitrate yielding a dinitrosyl complex." Dalton Transactions 49, no. 5 (2020): 1681–87. http://dx.doi.org/10.1039/d0dt00077a.

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7

Doyle, Michael P., та Yong-Liang Su. "Application of α-Aminoalkyl Radicals as Reaction Activators". Synthesis 54, № 03 (3 листопада 2021): 545–54. http://dx.doi.org/10.1055/a-1685-2853.

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Abstractα-Aminoalkyl radicals are easily accessible through multiple pathways from various precursors. Apart from their utilization as nitrogen-containing building blocks, they have recently been used as halogen atom abstraction reagents or single-electron reductants to transform organic halides or sulfonium salts into their corresponding highly reactive radical species. Benefiting from the richness of various halides and the diverse reactivity of radical intermediates, new transformations of halides and sulfonium salts have been developed. This short review summarizes this emerging chemistry that uses α-aminoalkyl radicals as the reaction activators.1 Introduction2 Activation of Halides as Halogen-Atom Transfer Agents2.1 Addition to Unsaturated Bonds2.1.1 Addition to C=C Bonds2.1.2 Addition to C=O Bonds2.2 Substitution Reactions2.2.1 Deuteration2.2.2 Olefination2.2.3 Allylation2.2.4 Aromatic Substitution2.2.5 Amination3 Activation of Sulfonium Salts as Single-Electron Reductants4 Conclusion and Outlook
8

Irmeilyana, Irmeilyana, Ngudiantoro Ngudiantoro, and Sri Indra Maiyanti. "REGRESSION MODEL ON PAGARALAM COFFEE FARMERS’ INCOME WITH THE INFLUENCE OF THE USE OF HERBICIDE REDUCTANT VARIABLE." BAREKENG: Jurnal Ilmu Matematika dan Terapan 16, no. 2 (June 1, 2022): 409–20. http://dx.doi.org/10.30598/barekengvol16iss2pp409-420.

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The existence of weeds in coffee fields will become competitors for coffee plants, so that they can be economically and ecologically detrimental. Inappropriate use of chemical herbicides can have a negative impact. Herbicide reductants made from organic are used in weed control. This study aims to analyze the variables that affect the net income of Pagaralam coffee farmers using multiple linear regression analysis. One of these variables is a qualitative variable in the form of categories of respondents based on the use of herbicide reductants. The data used was obtained from the results of questionnaires on 56 respondents who are users and 80 respondents who are not users of herbicide reductants. The results of the hypothesis test of mean difference found that the net income of the two respondent categories is not different. The regression analysis also resulted that there was no significant difference in net income between the two respondent categories. Variables that had a significant effect on net income included gross income, farming maintenance costs, estimated yields, and tree age. Several models also contain variables of land area, length of time in coffee farming, number of trees, and frequency of organic fertilizers used. Old coffee trees should be treated better with the use of organic fertilizers and also wise weed control techniques.
9

Yuan, Tao, Meifang Zheng, Markus Antonietti, and Xinchen Wang. "Ceramic boron carbonitrides for unlocking organic halides with visible light." Chemical Science 12, no. 18 (2021): 6323–32. http://dx.doi.org/10.1039/d1sc01028j.

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10

Guo, Wei, Yongbin Zhang, and Guofu Zhou. "Tetrahydropyrimidine Derivatives as Efficient Organic Reductants for Transfer Hydrogenation." HETEROCYCLES 78, no. 6 (2009): 1541. http://dx.doi.org/10.3987/com-08-11603.

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Статті в журналах

Дисертації з теми "Organic reductants":

1

Zuluaga, Villamil Maria Alejandra. "New routes for activation of transition metal complexes : Generation of low valent metal species for catalysis using organic reductants." Electronic Thesis or Diss., Lyon, École normale supérieure, 2024. http://www.theses.fr/2024ENSL0006.

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Cette thèse a pour premier objectif de développer et rationaliser l’utilisation de réducteurs organiques pour la synthèse de complexes organométalliques de basse valence. Plus précisément, cette thèse évalue le potentiel des réducteurs organosilylés pour la réduction contrôlée des complexes organométalliques à base de Ti et de W impliqués dans la réaction d'oligomérisation de l'éthylène, une réaction très importante au niveau industriel, et source de nombreux débats mécanistiques. Pour répondre à ces questions, des expériences de voltampérométrie cyclique ont été réalisées pour étudier les propriétés redox de ces systèmes. L'impact de facteurs externes tels que la température et le solvant sur le potentiel redox a également été examiné. Parallèlement à cette approche expérimentale, des calculs DFT sont venus complétés ce travail afin de tenter d’anticiper la valeur ce potentiel redox pour toute une gamme de réducteurs organiques. Dans un deuxième objectif, la synthèse des complexes de W(IV) et de Ti(II) a été spécifiquement adressée afin notamment (i)- d’élucider la réactivité des complexes de W(IV) en oligomérisation de l’éthylène (mécanismes de Cossee-Arlman ou metallacycle), et (ii)- proposer des nouvelles voies de synthèse de complexes de Ti(II) cationiques qui n’utiliseraient pas le MAO (methylaluminoxane), un co-catalyseur mal défini et pourtant couramment utilisé en oligomérisation. Ce travail de thèse pose ainsi les bases d’une utilisation rationnelle des réducteurs organiques et de leur mise en œuvre en catalyse
The first objective of this thesis is to develop and rationalize the use of organic reducing agents for the synthesis of low-valent organometallic complexes. More precisely, this thesis evaluates the potential of organosilylated reductants for the controlled reduction of organometallic complexes based on Ti and W involved in the ethylene oligomerization reaction, a very important reaction at the industrial scale, and source of numerous mechanistic debates. To answer these questions, cyclic voltammetry experiments were carried out to study the redox properties of these systems. The impact of external factors such as temperature and solvent on the redox potential was also examined. Alongside this experimental approach, DFT calculations completed this work to anticipate the value of this redox potential for a whole range of organic reductants. In a second objective, the synthesis of W(IV) and Ti(II) complexes was specifically addressed in particular to (i)- elucidate the reactivity of W(IV) complexes in ethylene oligomerization (Cossee-Arlman or metallacycle mechanism), and (ii)- propose new routes for the synthesis of cationic Ti(II) complexes which would not use MAO (methylaluminoxane), a poorly defined co-catalyst yet commonly used in oligomerization. This thesis work thus lays the foundations for a rational use of organic reducers and their implementation in catalysis
2

Cushman, Christopher Scott. "Destruction of chlorinated hydrocarbons by zero-valent zinc and bimetallic zinc reductants in bench-scale investigations." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1398342299.

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3

Mork, Anna Jolene. "Novel reactions of a neutral organic reductant : reductive coupling and nanoparticle synthesis." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/73438.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2012.
Vita. Cataloged from PDF version of thesis.
Includes bibliographical references (p. 53-55).
A recently developed bis-pyridinylidene neutral organic electron donor captured our interest as a potential source of new chemistries for reductive coupling and the synthesis of group IV nanoparticles. This super electron donor was used as a co-reductant for nickel-catalyzed reductive coupling of aryl halides in order for the reaction to be homogeneous and avoid the traditional co-reductant, zinc, previously reported for these Yamamoto-type dehalogenative couplings. Reductive coupling was somewhat successful for specific substrates, including 4- bromoanisole and 2,5-dibromothiophene, but competing hydrodehalogenation of the aryl halide was problematic for both expanding the substrate scope and increasing the length of the polymers generated from this reaction. The attempt to synthesize silicon and germanium nanoparticles from reduction of the corresponding tetrachloride precursors using this super organic electron donor met limited success. Dimerization of silicon species occurred, but there was little conclusive evidence of nanoparticle formation. Finally, in a brief side-project to explore other applications of the organic reductant, the molecule was shown to successfully n-dope both p-type and n-type organic electronic materials.
by Anna Jolene Mork.
S.M.
4

Robescu, Marina Simona. "Discovery and characterization of new Ene-reductases." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3426346.

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Seven new putative ene-reductases (ERs or OYEs) have been identified and selected using bioinformatics tools from different organisms: Galdieria sulphuraria (GsOYE), Chroococcidiopsis thermalis (CtOYE), Chloroflexus aggregans (CaOYE), Botryotinia fuckeliana (BfOYE1 and BfOYE4) and Aspergillus niger (AnOYE2 and AnOYE8). Based on most updated literature, both the photosynthetic organisms (Galdieria, Chroococcidiopsis and Chloroflexus) and the fungi (Botryotinia and Aspergillus) result very interesting sources for ERs, that have not been exploited until now. The cloning and expression strategy used was the same for all the seven putative sequences. After a first trial of expression in E. coli BL21(DE3 good over-expression and solubility were obtained for GsOYE, CtOYE, CaOYE and BfOYE1 while for the other three proteins further optimization was necessary. To overcome the low solubility of AnOYE2 and AnOYE8 and the low production of BfOYE4 many strategies have been performed such as lowering the temperature of expression and using chaperons, but also trying other expression hosts (i.e. P. pastoris). A biocatalytic characterization was carried out for all proteins. Once verified their activity as ene-reductases in vitro, a steady-state study was performed in order to obtain the kinetics parameters. For two enzymes, GsOYE and CtOYE, bioconversions were set-up at the Biocatalysis laboratories of Graz University headed by Prof. Kurt Faber, a main expert of biocatalysis and also of ene-reductases. Finally, a biochemical characterization was carried on in order to determine the thermal stability, pH tolerance and also the three-dimensional structure of the newly discovered enzymes. Moreover, their application for the hydride-independent isomerization of non-activated C=C-bonds and subsequent reduction is also discussed and the efforts in elucidating this new reactivity are shown in detail. The work presented in this thesis lead to the discovery of new ERs enlarging the possibility to find out novel and promising biocatalysts for C=C-bond bioreduction but also for other unexpected biocatalytic reactivities.
Sette nuove ene-reduttasi putative sono state identificate attraverso mezzi bioinformatici con un approccio di “genome mining” da diversi organismi: Galdieria sulphuraria (GsOYE), Chroococcidiopsis thermalis (CtOYE), Chloroflexus aggregans (CaOYE), Botryotinia fuckeliana (BfOYE1 and BfOYE4) e Aspergillus niger (AnOYE2 and AnOYE8). In particolare gli organismi fotosintetici (Galdieria, Chroococcidiopsis e Chloroflexus) e i fungi (Botryotinia e Aspergillus) sono, ad oggi, fonti di ene-reduttasi rimaste inesplorate. Per il clonaggio e l’espressione di tutte e sette le sequenze codificanti le proteine di interesse è stata utilizzata una strategia comune. Inizialmente tutte le proteine sono state espresse utilizzando come ospite E. coli BL21(DE3); con questa strategia, però, sovraespressione e buona solubilità sono state ottenute solo per quattro delle sette proteine, GsOYE, CtOYE, CaOYE e BfOYE1. Per le altre tre proteine è stata necessaria un’ulteriore ottimizzazione. La bassa solubilità di AnOYE2 e AnOYE8 e la scarsa espressione di BfOYE4 sono state affrontate utilizzando diverse strategie, come la diminuzione della temperatura e l’utilizzo di chaperonine ma anche l’utilizzo di altri ospiti per l’espressione proteica (P. pastoris). Per tutte e sette le proteine ricombinanti è stata condotta una caratterizzazione biocatalitica. Una volta dimostrata la loro attività come ene-reduttasi in vitro, sono stati determinati anche i parametri cinetici per i substrati preferiti da ciascun enzima. Nel laboratorio del Professor Kurt Faber dell’Università di Graz, sono state messe a punto bioconversioni per i due enzimi GsOYE e CtOYE, al fine di capirne il profilo di selettività nei confronti di substrati standard. Infine, è stata condotta anche una caratterizzazione biochimica che ha permesso di determinare la stabilità termica e la tolleranza a diversi pH dei nuovi enzimi identificati; per i quali è stata anche ottenuta la struttura tridimensionale. Nella tesi è discusso l’utilizzo degli enzimi nell’isomerizzazione NADH-indipendente di substrati con legami C=C non attivati e la loro successiva riduzione, così come gli sforzi per chiarire il meccanismo d’azione di questa nuova reattività scoperta solo di recente. Il lavoro presentato ha portato alla scoperta di nuove ene-reduttasi, ampliando così il pannello dei biocatalizzatori disponibili per la riduzione del doppio legame C=C ma anche per reattività biocatalitiche inaspettate.
5

Mudgal, Mukesh M. Dr. "Insight Into the Inhibition of Ribonucleotide Reductases by 2'-chloro-2'-deoxynucleotides and 2'-azido-2'-deoxynucleotides: Biomimetic Studies with Model Substrates." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2597.

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Ribonucleotide Reductases (RNRs) are crucial enzymes that catalyze reduction of ribonucleotides to deoxyribonucleotides, required for the biosynthesis of DNA. Vital role played by RNR in the biosynthesis of DNA and its control on cell growth made it one of the main targets for anticancer therapy. Several laboratories clarified the aspects of reaction cascades at active site of RNR. Biochemical studies of RNR by Stubbe for the inactivation of RDPR by 2'-chloro-2'-deoxyuridine-5'-diphosphate emphasizes departure of chlorine as an anion, while biomimetic studies by Robins with 6'-O-nitro-2'-chloro-homonucleosides emphasizes the elimination of chlorine substituent from 2'-position as a radical. To clarify the ambiguity in the mechanism of inhibition of RNR by 2'-chloro-2'-deoxyuridine, biomimetic reactions with model 6-O-nitro-1,5-dideoxyhomosugar derivatives were investigated. The study includes several modes: (i) synthesis of 6-O-nitro-1,5-dideoxyhomosugar derivatives with chlorine, bromine or tosyl substituent at the C2 position with ribo and arabino configurations, (ii) biomimetic studies of 6-O-nitro-1,5-dideoxyhomosugar derivatives with Bu3SnH/AIBN to provide chemical evidences to distinguish the nature of elimination of chlorine from 2'-chloro-2'-deoxyuridine upon its incubation with enzyme, and (iii) kinetic studies to differentiate between heterolytic or homolytic C2'-chlorine bond cleavage. In the second half of this dissertation, azido and sulfenamide modified nucleosides and 2-azidolyxofuranoside derivatives have been synthesized with the azido or sulfenamide substitution at a specific site in the sugar or in the base moiety. The electron-induced site specific formation of neutral aminyl radicals (RNH●) and their subsequent reactions have been investigated using ESR spectroscopy. In 2'-AZdC the RNH● site is attached to a 2o C-atom, where as in 4'-AZdC, the RNH● site is attached to a 3o C-atom, respectively. These studies elucidated how stereo and electronic environment affect formation and subsequent reactivity of various types of RNH● generated from azidonucleosides. To avoid the interaction of transient radical with nucleoside heterocyclic bases, 2-azidolyxofuranoside derivatives as a simpler abasic model were synthesized and studied with ESR spectroscopy. Aminyl radical generated from 2-azidolyxofuranoside derivatives subsequently abstracted hydrogen from C5 intramolecularly. These studies were designed to understand the mechanism of damage in various DNA model structures.
6

Dang, Thao P. "Biomimetic Modeling of the Nitrogen-centered Radical Postulated to occur during the Inhibition of Ribonucleotide Reductases by 2'-Azido-2'-deoxynucleotides." FIU Digital Commons, 2010. http://digitalcommons.fiu.edu/etd/318.

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Ribonucleotide reductases (RNR) are essential enzymes that catalyze the reduction of ribonucleotides to 2'-deoxyribonucleotides, which is a critical step that produces precursors for DNA replication and repair. The inactivation of RNR, logically, would discontinue producing the precursors of the DNA of viral or cancer cells, which then would consequently end the cycle of DNA replication. Among different compounds that were found to be inhibitors of RNR, 2'-azido-2'-deoxynucleotide diphosphates (N3NDPs) have been investigated in depth as potent inhibitors of RNR. Decades of investigation has suggested that the inactivation of RNR by N3NDPs is a result of the formation of a nitrogen-centered radical (N•) that is covalently attached to the nucleotide at C3' and cysteine molecule C225 [3'-C(R-S-N•-C-OH)]. Biomimetic simulation reactions for the generation of the nitrogen-centered radicals similar to the one observed during the inactivation of the RNR by azionuclotides was investigated. The study included several modes: (i) theoretical calculation that showed the feasibility of the ring closure reaction between thiyl radicals and azido group; (ii) synthesis of the model azido nucleosides with a linker attached to C3' or C5' having a thiol or vicinal dithiol functionality; (iii) generation of the thiyl radical under both physiological and radiolysis conditions whose role is important in the initiation on RNR cascades; and (iv) analysis of the nitrogen-centered radical species formed during interaction between the thiyl radical and azido group by electron paramagnetic resonance spectroscopy (EPR). Characterization of the aminyl radical species formed during one electron attachment to the azido group of 2'-azido-2'-deoxyuridine and its stereospecifically labelled 1'-, 2'-, 3'-, 4'- or 5,6-[2H2]-analogues was also examined. This dissertation gave insight toward understanding the mechanism of the formation of the nitrogen-centered radical during the inactivation of RNRs by azidonucleotides as well as the mechanism of action of RNRs that might provide key information necessary for the development of the next generation of antiviral and anticancer drugs.
7

Elatawy, M. A. K. "SYNTHESIS OF NITROGEN HETEROCYCLES BY INTRAMOLECULAR CYCLIZATION OF ALPHA, BETA-UNSATURATED NITRO COMPOUNDS, CATALYZED BY PALLADIUM COMPLEXES AND WITH CARBON MONOXIDE AS THE REDUCTANT." Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/331319.

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This work consists of four main parts. Part I describes the synthesis of medicinally relevant indoles by palladium-catalyzed reductive cyclization of readily obtainable β-nitrostyrenes using carbon monoxide as the reductant and in acetonitrile as a solvent. Part II describe a new route to synthesize thieno[2,3-b]pyrrole or thieno[3,2-b]pyrrole by intramolecular reductive cyclization of α,β-unsaturated nitro compounds using carbon monoxide as the reductant and catalyzed by palladium complexes. Part III presents our work on palladium catalyzed intramolecular reductive cyclization of nitro-dienes with carbon monoxide, which provides a novel and efficient method for synthesis of 2,5-disubstituted or 2,3,5-trisubstituted pyrroles.
8

Dai, Ren-Tai, and 戴仁泰. "Reclamation of heavy metals contaminated soils using chemical reductant combined with dissolved organic carbon solution." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/64457376737395961116.

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碩士
國立宜蘭大學
環境工程學系碩士班
103
Illegal discharges of untreated wastewaters from electroplating and electronics factories have been found causing serious contamination of croplands with toxic metals in Taiwan. Though acid washing is a highly efficient method to clean the metals away a soils, it always causes clear loss of fertility. In addition, sometimes it’s difficult to decline the concentrations of toxic metals below the control threshold using traditional acid washing and dissolved organic carbon (DOC) washing, when treating a severely polluted soil. In this study, chemical reductants were employed to dissolve the surfaces of Fe and Mn oxides for more release of the toxic metals under a moderate-acid condition. Soil samples, containing high concentrations of Cr, Cu, Zn, Ni, Cd, and Pb, as well as nine reductants, including sodium thiosulfate, sodium bisulfite, hydroxylamine sulfate, hydroxylamine hydrochloride, stannous chloride, vitamin C, sodium dithionite, sodium sulfite, and ferrous chloride, were collected and used to conduct experiments of soil washing. The DOC solution, extracting form the waste distillery sludge, served as a second washing reagent. It was believed that DOC would encourage the removal of toxic metals and take off the reductants remained in soil through previous washing. The factors affecting the removals of metals, including pH, the concentration of a chemical reducing agent, DOC concentration of the solution, the solid-liquid ratio, reaction time, temperature, soaking time and other parameters were examined in this study. Variations in soil fertility during the washing were also examined. Approximately 54.4, 53.7, 16.8, and 3.6 % of Cu, Ni, Zn, and Cr were respectively removed from a soil, which contaminated with Cu (367 ppm), Ni (352 ppm), Zn (712 ppm), and Cr (257 ppm), through the “0.6 M FeSO4+DOC” treatment at pH 2.0; the result accomplished the purpose of remediation. Another soil with higher contents of metals, Cu (502 ppm), Ni (413 ppm), Zn (712 ppm), and Cr (336 ppm), could be remediated well by “0.2 M Na2S2O4+ DOC” treatment; about 84.8% (Cu), 45.3% (Ni), 23.4% (Zn), 30.1% (Cr) were removed from the soil. After washing with 0.2 M Na2S2O4 / DOC mixture or 0.6 M FeSO4 / DOC mixture, Cd contents in topsoil and subsoil were declined from 21.5 and 19.9 ppm to 3.4 and 4.3 ppm, respectively; this result also met the control standard. However, the Pb contentsl were decreased from 5340 to 2173 and 2652 ppm by treating with 0.2 M Na2S2O4 / DOC mixture and 0.6 M FeSO4 / DOC mixture, respectively; this might be due to its high original content of Pb and the result did not met the control standard (500 ppm). To summarize the changes in fertility during DOC washing with various reagents: the average increase in organic matter content was 15%; available ammonium (NH4+-N) content was 3.9 times; and exchangeable K was 33%. The average decreases in available phosphorus, exchangeable Ca, and exchangeable Mg contents were 10%, 11%, and 10%, respectively. This indicates that most fertility can be reserved by the DOC washing.

Частини книг з теми "Organic reductants":

1

Gompper, K. "Alternative Organic Reductants for Denitration." In Denitration of Radioactive Liquid Waste, 32–46. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-011-9757-1_3.

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2

Stone, Alan T. "Adsorption of Organic Reductants and Subsequent Electron Transfer on Metal Oxide Surfaces." In ACS Symposium Series, 446–61. Washington D.C.: American Chemical Society, 1987. http://dx.doi.org/10.1021/bk-1987-0323.ch021.

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3

Hayat, Tahir, Wen Xia, Yan He, Haizhen Wang, Jianjun Wu, and Jianming Xu. "Humic Substances as a Reductant for Hydrophobic Organic Compounds." In Functions of Natural Organic Matter in Changing Environment, 641–45. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-94-007-5634-2_116.

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4

Simon, Helmut, Helmut Günther, Johann Bader, and Stefan Neumann. "Chiral Products from Non-Pyridine Nucleotide-Dependent Reductases and Methods for NAD(P)H Regeneration." In Ciba Foundation Symposium 111 - Enzymes in Organic Synthesis, 97–111. Chichester, UK: John Wiley & Sons, Ltd., 2008. http://dx.doi.org/10.1002/9780470720929.ch8.

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5

Flowers, R. A. II, T. V. Chciuk, and C. O. Bartulovich. "2.2 Samarium-Mediated Reductions." In Free Radicals: Fundamentals and Applications in Organic Synthesis 2. Stuttgart: Georg Thieme Verlag KG, 2021. http://dx.doi.org/10.1055/sos-sd-233-00001.

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AbstractSamarium(II)-based reductants have been shown to be a group of very powerful reagents whose reactivity can be tuned significantly by the use of additives. The use of additives has been shown to greatly impact the rate, diastereoselectivity, chemoselectivity, and mechanism by which these reactions proceed, making these systems extremely useful and versatile. These reagents have been shown to promote several reactions including reductions of a range of functional groups and a variety of carbon–carbon bond forming reactions. More recently, initial work has demonstrated catalytic reactions of samarium(II)-based reductants. This chapter focuses on the chemistry of samarium diiodide (SmI2) and a few other samarium(II)-based reductants, with examples of the reactions they promote, both with and without the use of additives. Additionally, recent work on the mechanistic understanding of catalytic reactions using terminal reductants and a novel example of an approach employing radical relay that negates the use of a terminal reductant are presented.
6

Sumida, Y., and H. Ohmiya. "4.4.23.7 Silylmethyl Anions (Update 2022)." In Knowledge Updates 2022/3. Stuttgart: Georg Thieme Verlag KG, 2022. http://dx.doi.org/10.1055/sos-sd-104-00799.

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AbstractSilylmethyl anions have found various applications in synthesis, including as nucleophiles, metalation reagents, reductants, and stabilization ligands for other metals. The unique property arising from the α-anion stabilization effect and transformability of the silyl substituent allows synthetically useful methodology, enabling olefination, homologation, selective metalation, and further transformations. Thus, these synthetic reagents remain valuable and are widely employed in modern organic synthesis. This chapter describes the advancement of silylmethyl anion chemistry, with the major developments from 2000 to the present date covered.
7

Barlow, Stephen, Seth R. Marder, Xin Lin, Fengyu Zhang, and Antoine Kahn. "Electrical Doping of Organic Semiconductors with Molecular Oxidants and Reductants." In Conjugated Polymers, 21–43. CRC Press, 2019. http://dx.doi.org/10.1201/9780429190520-2.

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8

Kobayashi, Shu. "Tin Lewis acid." In Lewis Acid Reagents, 137–57. Oxford University PressOxford, 1999. http://dx.doi.org/10.1093/oso/9780198500995.003.0007.

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Abstract The element tin has played an increasingly important role in organic chemistry as well as organometallic chemistry, serving as a source of new reagents for selective transformations.1-3 The main activity in these fields has been focused for a long time on tin(IV) compounds, and tin(II) compounds have been used primarily as reductants of aromatic nitro compounds to aromatic amines.4 During the last decade, asymmetric synthesis has been developed increasingly, and in this field tin(II) reagents have served main roles rather than tin(IV) reagents.
9

Jose, Jerin, Raj Kamal Singh, and Ligy Philip. "Pulsed power technology for water and wastewater treatment." In Technological Solutions for Water Sustainability: Challenges and Prospects, 133–44. IWA Publishing, 2023. http://dx.doi.org/10.2166/9781789063714_0133.

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The presence of recalcitrant and hazardous water pollutants poses a serious challenge to conventional water treatment technologies and is motivating the development of advanced treatment approaches like pulsed power technology (PPT). One application of PPT is to generate plasma that can be used for the efficient and rapid degradation of a wide range of emerging water pollutants, including dyes, pesticides, toxic solvents, and pharmaceuticals, and for the disinfection of water and wastewater. Plasma-based water treatment utilizes electrical discharge plasmas formed in contact with or in the vicinity of water to degrade chemicals within the contaminated water. Plasma in these conditions can produce a diverse range of highly reactive species, including strong oxidants (•OH) and reductants (eˉaq), which are suitable for the simultaneous oxidation and reduction of the organic compounds present in highly complex wastewater such as industrial effluents. PPT exhibits the advantages of fast pollutant degradation kinetics, relatively low energy input, and the absence of chemical additives, making it a promising alternative water treatment technology. The increasing demand for water treatment technologies for treating hazardous chemicals with no/minimal generation of secondary pollutants may accelerate the adoption of safe and energy-efficient technologies like PPT.
10

"Imine Reductases." In Biocatalysis in Organic Synthesis, edited by Faber, Fessner, and Turner. Stuttgart: Georg Thieme Verlag, 2015. http://dx.doi.org/10.1055/sos-sd-215-00205.

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Тези доповідей конференцій з теми "Organic reductants":

1

Patel, J. "Role of Plasma-Induced Liquid Chemistry for the Reduction Mechanism of Silver Ions to form Silver Nanostructures." In Functional Materials and Applied Physics. Materials Research Forum LLC, 2022. http://dx.doi.org/10.21741/9781644901878-7.

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Abstract. There exists a variety of reports on the synthesis of silver nanostructures by plasma-liquid interactions; however seldom are those that discusses the underlying reaction kinetics. The present study focuses in such direction where the role of plasma-induced chemistry has been analysed in detail with the reports on the influence of radicals on the formation of silver nanostructures. The silver nanostructures are synthesized from various precursor concentrations of silver and characterized byultraviolet-visible spectroscopy and transmission electron microscopy analysis. Further, experiments have been carried out to clarify the role of reductants in silver nanostructures synthesis. It is found that hydrogen peroxide is unable to reduce the silver ions to silver atoms which is a necessary step to produce silver nanostructures. The addition of organic solvents such as methanol and ethanol has been found to enhance the production rate of silver nanostructures which indicates that methanol and ethanol are strong electron donors affecting the reduction process of silver ions. In order to probe the exact reaction mechanism for silver nanostructures synthesis, iodine has been used as hydrogen radical scavenger along with silver precursor solutions; however, it has been observed that addition of iodine ions generates a favourable condition for the reduction of silver ions. The ultraviolet-visible spectroscopy results indicate the existence of small clusters of silver ions and silver iodide and further transmission electron microscopy characterization suggests that a well-dispersed silver nanoparticles of less than 30 nm in size have been formed. The lattice spacing calculation from transmission electron microscopy images suggests the presence of crystallinity of the particles. Overall, it is found that there are two possible ways for the reduction mechanism of silver nanostructures: either via hydrated electrons or hydrogen radicals or both.
2

Zehnle, H. S., R. Laso Pérez, A. Boetius, and G. Wegener. "Thermophilic Archaea Activate Liquid Alkanes Using Divergent Methyl-Coenzyme M Reductases." In 30th International Meeting on Organic Geochemistry (IMOG 2021). European Association of Geoscientists & Engineers, 2021. http://dx.doi.org/10.3997/2214-4609.202134206.

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3

Machado, Serly Santiago, Enesio Rodriguez Nascimento Neto, Elisa Teshima, Osmar Calderon Sanchez, Heiddy Marquez Alvarez, Ivan Sergio Colás Gonzáles, Luis Fernando Pascholati Gusmão, and Angélica Maria Lucchese. "Screening of keto reductases expressed in conidial fungi from the Brazilian semi-arid region." In 14th Brazilian Meeting on Organic Synthesis. São Paulo: Editora Edgard Blücher, 2013. http://dx.doi.org/10.5151/chempro-14bmos-r0050-1.

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4

Mikheykin, S. V., P. P. Poluektov, S. L. Khrabrov, A. Yu Smirnov, and V. P. Simonov. "D&D Experience in VNIINM." In ASME 2003 9th International Conference on Radioactive Waste Management and Environmental Remediation. ASMEDC, 2003. http://dx.doi.org/10.1115/icem2003-4769.

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Since the mid-1960s the VNIINM has been developing decontamination techniques for a variety of materials and contaminants for Russian nuclear engineering needs. 1. Early in the development, chemical decontamination was the most commonly used method. According to the nature of contaminants and contaminated material, mineral acids, alkali, mineral and organic oxidants and reductants were used. For best results, complex forming agents were sometimes added. However, in spite of widespread use of chemical decontamination at the USSR nuclear facilities, this technique has a drawback of producing a great deal of secondary liquid radwaste. Since the early 1970s attention has focused on the reduction of radwaste. Currently, optimized electrochemical and strippable coating methods are showing the greatest promise. 2. A low-waste dry decontamination technique based on application of readily strippable polymeric (protecting, decontaminating, immobilizing) coats has been developed and tested in the laboratory and wide scale. A low-waste dry decontamination technique based on application of readily strippable polymeric (protecting, decontaminating, immobilizing) coats has been developed and tested in the laboratory and wide scale. 3. VNIINM has developed a few electrochemical decontamination procedures and equipment surface decontamination. 4. One of VNIINM’s laboratory rooms which had been put to prolonged storage after an incidental alpha-radioactivity release was chosen for tests and demonstration. At first, the radioactivity levels inside the room on all the surfaces were measured. On outer surfaces, the alpha-activity was 1–15 α-particles/min.cm2, the gammaactivity varied from 720 to 2880 mkrem/s. The room was equipped with instrumentation and apparatures located in three chains of gloveboxes and hot cells for handling Pu-bearing materials. Continuous checks of the airborne radioactivity and the personnel residence time inside the room were performed. 5. Old Pu extraction facility (U-5) was decontaminated and decommissioning in VNIINM in 1999–2000. This facility is a system of interconnected working areas housing process equipment located in 4 floor building and includes more than 20 laboratories rooms, 2 “hot cells”, few sealed contaminated rooms and two extraction shaft. Industrial separation technologies have been tested on the facility for 20 years since 1947. The first USSR Pu was obtained here. Practically all rooms were contaminated with Pu, Cs, Sr etc. The experimental equipment of two hot cells (63 m2 each cell) control and service rooms was decontaminated and certified. The dissolution equipment, the metering tank compartment was decommissioned and removed. 16 laboratory rooms with a total area of 300 m2 were rehabilitated and certified. The amount of waste removed exceeded 12 500 kg. All rooms rehabilitated were certified and accepted by sanitary control service for further use. 6. At the time old contaminated room contains a non standard radiochemical equipment includes glove boxes is under decommissioning procedure. This project started at 2002.
5

Newburry, Don, Pat Runnels, and Mike Owings. "Selective Catalytic Reduction (SCR) System Installation and Commissioning at the Chow II Power Plant in Chowchilla, California." In ASME 2003 Internal Combustion Engine Division Spring Technical Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/ices2003-0594.

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Lean burn, natural gas, reciprocating engines are becoming widely utilized for stationary industrial applications due to their high efficiency and low emissions. However, despite the low engine emissions, some locations still require exhaust after-treatment to meet the local emissions requirements. Due to the high oxygen content (greater than 4%) in the exhaust of lean burn engines, 3-Way (non-selective) catalysts are not suitable to reduce NOx. Selective catalytic reduction (SCR), which utilizes a consumable reductant to reduce NOx over a catalyst, is very effective at reducing NOx and is becoming an accepted technology for large, stationary engine applications. In the summer of 2001, Stewart & Stevenson installed 16 Deutz TGB632V16 natural gas fired engines for NEO Corporation at the Chow II power plant. MIRATECH SCR provided and commissioned 16 selective catalytic reduction systems for these engines using a 40% urea solution as the reductant. This paper describes the installed SCR systems and reports some of the emissions testing results and costs. With the SCR systems in place, the engines were successfully able to meet the permitted exhaust emissions requirements of 0.07 g/bhp-hr of NOx, 0.1 g/bhp-hr of CO, and 0.15 g/bhp-hr of VOC’s (volatile organic compounds) with less than 10 ppmvd of ammonia slip @ 15% O2. Additional measurements were made of formaldehyde and acrolein. Very low levels of these emissions were found after the SCR.
6

Paviet-Hartmann, Patricia, Ana Nunez Gomez-Aleixandre, Joshua Pak, Amparo Glez Espartero, Frederic Poineau, Amber Wright, Edward Mausolf, and Kenneth R. Czerwinski. "Extraction of Technetium as [Tc(II)(NO)(AHA)2H2O]+ Species in the UREX Process." In 17th International Conference on Nuclear Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/icone17-75509.

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As it is envisioned today, the first segment of the UREX+ process uses low nitric acid concentrations for U(VI) extraction where pertechnetate anion, TcO4−, can be co-extracted with the uranyl and nitrate into TBP-hydrocarbon solutions. A reductant complexant, acetohydroxamic acid (AHA) is added to the process through the scrub to limit the extractability of plutonium and neptunium. Recent work performed in our laboratory (Ref. 1) demonstrated that TcO4− undergoes reductive nitrosylation by AHA under a variety of conditions. The resulting divalent technetium is complexed by AHA to form the pseudo-octahedral trans-aquonitrosyl-(diacetohydroxamic)-technetium(II) complex ([Tc(II)(NO)(AHA)2H2O]+). In this paper, we are reporting the extraction of [Tc(II)(NO)(AHA)2H2O]+ complex by new designed macrocompounds as well as commercially available crown ethers from 18-crown-6 to 24-crown-8 in ring size and of varying derivatization. Several organic diluents with different dielectric constants are used to enhance the distribution coefficient of technetium (II). The experimental efforts are focused on determining the best extraction conditions by varying the macrocomponds nature and concentration, and the organic phase composition.

Звіти організацій з теми "Organic reductants":

1

White, T. L., B. J. Wiedenman, D. P. Lambert, S. L. Crump, F. F. Fondeur, A. E. Papathanassiu, W. K. Kot, and I. L. Pegg. Organics Characterization Of DWPF Alternative Reductant Simulants, Glycolic Acid, And Antifoam 747. Office of Scientific and Technical Information (OSTI), October 2013. http://dx.doi.org/10.2172/1107775.

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2

Stone, A. T. Release of oxide-bound toxic metals by naturally-occurring and contaminant-derived organic compounds: The role of complexant, reductant, and adsorptive characteristics. Final report, July 1, 1994--June 31, 1997. Office of Scientific and Technical Information (OSTI), December 1997. http://dx.doi.org/10.2172/353369.

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