The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Wei-yuan Huang - One of the best experts on this subject based on the ideXlab platform.
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Studies on sulfinatodehalogenation: the addition reaction of halocarbons with olefins initiated by Sodium Dithionite
Journal of Fluorine Chemistry, 2001Co-Authors: Wei-yuan HuangAbstract:Abstract Halocarbons such as carbon tetrachloride, CCl 3 Br, CF 3 CCl 3 , BrCF 2 CF 2 Br, BrCF 2 CFClBr and CF 2 Br 2 , reacted with olefins in the presence of the sulfinatodehalogenation reagent Sodium Dithionite under mild conditions to give the corresponding adducts. In the case of F113, CFCl 2 CF 2 CFCl 2 and CF 3 Cl 3 , the polyfluoroalkylation product resulted.
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Sodium Dithionite initiated addition sulfination reaction of perfluoroalkyl bromides and olefins
Journal of Fluorine Chemistry, 1999Co-Authors: Jintao Liu, Gang Chen, Guo-dong Sui, Wei-yuan HuangAbstract:Abstract In the presence of Sodium Dithionite, perfluoroalkyl bromides reacted with olefins readily in aqueous iso-propanol solution under mild conditions, giving the corresponding addition–sulfination products, R F CH 2 CH(R)SO 2 Na, in good yields. A radical mechanism was proposed for this reaction.
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Sodium Dithionite initiated addition–sulfination reaction of perfluoroalkyl bromides and olefins
Journal of Fluorine Chemistry, 1999Co-Authors: Jin‐tao Liu, Guo-dong Sui, Gang Chen, Wei-yuan HuangAbstract:Abstract In the presence of Sodium Dithionite, perfluoroalkyl bromides reacted with olefins readily in aqueous iso-propanol solution under mild conditions, giving the corresponding addition–sulfination products, R F CH 2 CH(R)SO 2 Na, in good yields. A radical mechanism was proposed for this reaction.
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The addition of F113 and CFCl2CF2CFCl2 to alkenes promoted by Sodium Dithionite
Journal of Fluorine Chemistry, 1998Co-Authors: Wei-yuan HuangAbstract:Abstract The addition of F113 and CFCl2CF2CFCl2 to alkenes promoted by Sodium Dithionite occurs to give the corresponding fluoroalkylation products in moderate yields.
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Perfluoroalkylation initiated with Sodium Dithionite and related reagent systems
Journal of Fluorine Chemistry, 1992Co-Authors: Wei-yuan HuangAbstract:Abstract Perfluoroalkylations promoted by Sodium Dithionite and related reagent systems have been reported for the following groups of compounds, viz. (i) conjugated dienes, (ii) enol ethers, and (iii) aromatic and heteroaromatic compounds. The results of some chemical conversions of the reaction products for the synthesis of useful synthetic intermediates have also been presented. A comparison between the Dithionite initiated reaction and other related systems was made and discussed.
Xuefeng Jiang - One of the best experts on this subject based on the ideXlab platform.
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Sodium Dithionite mediated decarboxylative sulfonylation facile access to tertiary sulfones
Angewandte Chemie, 2020Co-Authors: Shihao Chen, Ming Wang, Xuefeng JiangAbstract:A straightforward multicomponent decarboxylative cross coupling of redox-active esters (N-hydroxyphthalimide ester), Sodium Dithionite, and electrophiles was established to construct sterically bulky sulfones. The inorganic salt Sodium Dithionite not only served as the sulfur dioxide source, but also acted as an efficient radical initiator for the decarboxylation. Notably, diverse naturally abundant carboxylic acids and artificially prepared carboxyl-containing drugs with multiple heteroatoms and sensitive functional groups successfully underwent this decarboxylative sulfonylation to provide sterically bulky tertiary sulfones. Mechanistic studies further demonstrated that decarboxylation was the rate-determining step and occurred via a single-electron transfer (SET) process with the assistance of Sodium Dithionite.
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Sodium Dithionite‐Mediated Decarboxylative Sulfonylation: Facile Access to Tertiary Sulfones
Angewandte Chemie (International ed. in English), 2020Co-Authors: Shihao Chen, Ming Wang, Xuefeng JiangAbstract:A straightforward multicomponent decarboxylative cross coupling of redox-active esters (N-hydroxyphthalimide ester), Sodium Dithionite, and electrophiles was established to construct sterically bulky sulfones. The inorganic salt Sodium Dithionite not only served as the sulfur dioxide source, but also acted as an efficient radical initiator for the decarboxylation. Notably, diverse naturally abundant carboxylic acids and artificially prepared carboxyl-containing drugs with multiple heteroatoms and sensitive functional groups successfully underwent this decarboxylative sulfonylation to provide sterically bulky tertiary sulfones. Mechanistic studies further demonstrated that decarboxylation was the rate-determining step and occurred via a single-electron transfer (SET) process with the assistance of Sodium Dithionite.
Paul Kiekens - One of the best experts on this subject based on the ideXlab platform.
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a wall jet disc electrode for simultaneous and continuous on line measurement of Sodium Dithionite sulfite and indigo concentrations by means of multistep chronoamperometry
Analytica Chimica Acta, 2003Co-Authors: Emmanuel Gasana, Philippe Westbroek, Eduard Temmerman, H. P. Thun, Paul KiekensAbstract:Abstract In this paper, a multistep chronoamperometric method is presented to measure continuously and simultaneously the concentrations of indigo, Sodium Dithionite and sulfite for application in textile dyeing processes. The method is based on the oxidation of Sodium Dithionite and the reduced form of indigo at a platinum disc electrode. Sodium Dithionite is oxidized at a potential of 0.3 V versus Ag/AgCl and shows transport controlled steady state currents at a rotating disc electrode and a wall-jet electrode. The latter has been developed for the purpose of the application. Implementation of a wall-jet instead of a rotating disc electrode is much easier and cost-effective. Indigo is oxidized at −0.55 V versus Ag/AgCl to a virtually water insoluble product, which precipitates at the electrode surface. Indigo behaves quasi-reversibly, and is reduced at a potential of −0.9 V versus Ag/AgCl. In order to clean the electrode surface this reduction is used as a step in the multistep sequence. Finally, sulfite is oxidized at a potential of 0.8 V versus Ag/AgCl but did not give rise to well defined transport controlled limiting currents. However, determination of its concentration is still possible within error margins of 5%.
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Kinetics and mechanism of the oxidation of Sodium Dithionite at a platinum electrode in alkaline solution
Journal of Electroanalytical Chemistry, 2003Co-Authors: Emmanuel Gasana, Philippe Westbroek, E. Temmerman, K. De Wael, K. De Clerck, Paul KiekensAbstract:Abstract In this paper the oxidation of Sodium Dithionite in alkaline solution was studied by cyclic voltammetry at a stationary and rotating platinum disk electrode. The reaction proceeds in two steps, with sulfite as a relatively stable intermediate and sulfate as final product. It was possible to quantitatively analyze the kinetics of the oxidation wave making use of the experimental evidence that the reaction rate is not dependent on pH, with a reaction order of 0.5 with respect to Sodium Dithionite and a charge transfer coefficient of 0.5. The proposed mechanism of the overall electron transfer reaction consists of five consecutive steps starting with the adsorption of Dithionite, followed by decomposition into SO 2 − , which releases an electron in the rate determining step and finally two more chemical steps leading to the formation of sulfite. The predicted behavior by this mechanism is in agreement with the experimentally observed one.
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Improving Quality and Reproducibility of the Indigo Dye Process by Measuring and Controlling Indigo and Sodium Dithionite Concentrations
Textile Research Journal, 2003Co-Authors: Philippe Westbroek, Emmanuel Gasana, Paul Kiekens, Karen De Clerck, Eduard TemmermanAbstract:This paper describes a sensor system for continuous on-line and in-line measurement of indigo and Sodium Dithionite concentrations during textile dyeing with indigo. The system is based on an elect...
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development of voltammetric sensors for the determination of Sodium Dithionite and indanthrene indigo dyes in alkaline solutions
Analytica Chimica Acta, 1999Co-Authors: Filip Govaert, Eduard Temmerman, Paul KiekensAbstract:Abstract Linear sweep and cyclic voltammetric studies of indigo, indanthrene dyes and Sodium Dithionite in alkaline solutions are reported. The results were applied to develop amperometric determination methods for these vat dyes and reducing agent. On different electrode materials (Au, glassy carbon, Pd, Pt) the reduced dyes give an anodic voltammetric signal. This reaction referring to the oxidation of dyestuff is concentration, rotation and potential scan rate dependent. Adsorption of oxidized dyestuff on the electrode surface was found to impede the chronoamperometric determination. By introducing potential steps, in situ cleaning of the electrode surface leads to a repetitive renewal and activation of the electrode surface. The use of multi-pulse amperometry allowed to measure in a continuous way a voltammetric signal that is proportional to the dye concentration. The Sodium Dithionite concentration can also be monitored continuously using chronoamperometry but only in the absence of dyestuff due to the mentioned adsorption.
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Development of voltammetric sensors for the determination of Sodium Dithionite and indanthrene/indigo dyes in alkaline solutions
Analytica Chimica Acta, 1999Co-Authors: Filip Govaert, Eduard Temmerman, Paul KiekensAbstract:Abstract Linear sweep and cyclic voltammetric studies of indigo, indanthrene dyes and Sodium Dithionite in alkaline solutions are reported. The results were applied to develop amperometric determination methods for these vat dyes and reducing agent. On different electrode materials (Au, glassy carbon, Pd, Pt) the reduced dyes give an anodic voltammetric signal. This reaction referring to the oxidation of dyestuff is concentration, rotation and potential scan rate dependent. Adsorption of oxidized dyestuff on the electrode surface was found to impede the chronoamperometric determination. By introducing potential steps, in situ cleaning of the electrode surface leads to a repetitive renewal and activation of the electrode surface. The use of multi-pulse amperometry allowed to measure in a continuous way a voltammetric signal that is proportional to the dye concentration. The Sodium Dithionite concentration can also be monitored continuously using chronoamperometry but only in the absence of dyestuff due to the mentioned adsorption.
Carlos A. M. Afonso - One of the best experts on this subject based on the ideXlab platform.
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going beyond the limits of the biorenewable platform Sodium Dithionite promoted stabilization of 5 hydroxymethylfurfural
Chemsuschem, 2018Co-Authors: Rafael F. A. Gomes, Yavor Mitrev, Svilen P. Simeonov, Carlos A. M. AfonsoAbstract:The lack of thermal and storage stability and occurrence of side reactions during the processing of 5-hydroxymethylfurfural (5-HMF) limits its potential as biorenewable platform molecule. The addition of small amounts of the readily available Sodium Dithionite has a remarkable effect on promoting the stability of 5-HMF and inhibiting side reactions, thus helping to circumvent such limitations. The addition of Sodium Dithionite led to improvements in thermal stability (120 °C, 4 h, neat; 100 % vs. 37 %), under distillation (yield: 85 % vs. 52 %), and in a wide range of reactions, including 5-HMF synthesis under biphasic conditions (yield: 98 % vs. 67 %; purity: 92 % vs. 83 %) and 5-HMF transformations, such as Knoevenagel condensation with Meldrum's acid (yield: 96 % vs. 74 %), Cannizaro reaction (yield: quantitative vs. 83 %), and condensation with primary diamines to give pyridinium salts (yield: 88 % vs. 60 %).
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Going Beyond the Limits of the Biorenewable Platform: Sodium Dithionite‐Promoted Stabilization of 5‐Hydroxymethylfurfural
ChemSusChem, 2018Co-Authors: Rafael F. A. Gomes, Yavor Mitrev, Svilen P. Simeonov, Carlos A. M. AfonsoAbstract:The lack of thermal and storage stability and occurrence of side reactions during the processing of 5-hydroxymethylfurfural (5-HMF) limits its potential as biorenewable platform molecule. The addition of small amounts of the readily available Sodium Dithionite has a remarkable effect on promoting the stability of 5-HMF and inhibiting side reactions, thus helping to circumvent such limitations. The addition of Sodium Dithionite led to improvements in thermal stability (120 °C, 4 h, neat; 100 % vs. 37 %), under distillation (yield: 85 % vs. 52 %), and in a wide range of reactions, including 5-HMF synthesis under biphasic conditions (yield: 98 % vs. 67 %; purity: 92 % vs. 83 %) and 5-HMF transformations, such as Knoevenagel condensation with Meldrum's acid (yield: 96 % vs. 74 %), Cannizaro reaction (yield: quantitative vs. 83 %), and condensation with primary diamines to give pyridinium salts (yield: 88 % vs. 60 %).
Kwanghee Koh Park - One of the best experts on this subject based on the ideXlab platform.
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Convenient reduction of azobenzenes and azoxybenzenes to hydrazobenzenes by Sodium Dithionite using dioctylviologen as an electron transfer catalyst
Tetrahedron Letters, 1996Co-Authors: Kwanghee Koh Park, Sun Young HanAbstract:Abstract Various azobenzenes and azoxybenzenes were reduced almost quantitatively to the corresponding hydrazobenzenes by Sodium Dithionite under mild conditions without the formation of aniline derivatives, using dioctyl viologen as an electron-transfer catalyst in acetonitrile-water.
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Sodium Dithionite reduction of nitroarenes using viologen as an electron phase-transfer catalyst
Tetrahedron Letters, 1993Co-Authors: Kwanghee Koh Park, Won Kyou JoungAbstract:Abstract Various aromatic nitro compounds were reduced conveniently to the corresponding aniline derivatives with Sodium Dithionite using dioctyl viologen as an electron-transfer catalyst in dichloromethane- water two-phase system.
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viologen mediated reductive desulfonylation of α nitro sulfones by Sodium Dithionite
Journal of The Chemical Society-perkin Transactions 1, 1992Co-Authors: Kwanghee Koh Park, Sook Young ChoiAbstract:Reductive desulfonylation of α-nitro sulfones to give the corresponding nitro compounds was carried out conveniently with Sodium Dithionite, by using octylviologen as an electron-transfer catalyst in organic solvent–water two-phase systems. Sulfones which do not have an α-nitro group are not desulfonylated. A reaction scheme involving a nitroalkyl radical has been proposed.
