The Mechanism of the Disproportionation of Sulfinic Acids. Rate and Equilibrium Constants for the Sulfinic Acid-Sulfinyl Sulfone (Sulfinic Anhydride) Equilibrium1

1966 ◽  
Vol 31 (11) ◽  
pp. 3561-3567 ◽  
Author(s):  
John L. Kice ◽  
Giancarlo Guaraldi ◽  
Clifford G. Venier
Keyword(s):  
Equilibrium Constants ◽  
Sulfinic Acid ◽  
Sulfinic Acids

Accelerated Oxidations of Polyisoprene. II. Effects of Hydrazines, Sulfur Compounds, and Phenyl-β-Napthylamine in Solution

1968 ◽  
Vol 41 (2) ◽  
pp. 289-295 ◽  
Author(s):  
Frank R. Mayo ◽  
J. Heller ◽  
R. L. Walrath ◽  
Katherine C. Irwin
Keyword(s):  
Sulfur Compounds ◽  
Oxygen Absorption ◽  
Sulfinic Acid ◽  
Induction Periods ◽  
Sustained Effects ◽  
Low Concentrations ◽  
Sulfinic Acids ◽  
High Concentrations ◽  
A Chain ◽  
Future Work

Abstract At concentrations of 0.1 to 1 mM, phenylhydrazine causes marked decrease in viscosity of polyisoprene solutions in a few minutes at 50° C (see section II). This effect requires the presence of oxygen but no preoxidation of the rubber. Two molecules of oxygen are absorbed and about one fifth to one tenth of a chain is cleaved per molecule of phenylhydrazine added. The reaction is essentially complete within 20 min. This fast reaction is not much affected by the presence of antioxidants but results in the formation of some material (possibly phenolic) which reduces the effectiveness of other prooxidants. 1,1 -Dimethylhydrazine and 1,2-diphenylhydrazine, unlike phenylhydrazine, have slow but sustained effects. Hydrazine monohydrate is intermediate in its action. Investigation of the effects of several sulfur compounds on polyisoprene solutions brought out some striking effects and a need for further work. p-Thiocresol is a strong prooxidant for our polyisoprene solutions at concentrations below 0.2 mM. At higher concentrations, induction periods occurred with some, but not all, samples and could be shortened by the addition of t-butyl hydroperoxide. Di-p-tolyl disulfide was somewhat less active, but its effect increased regularly with its concentration. Other aryl thiols and disulfides had similar activity but benzyl derivatives did not. At low concentrations, benzene sulfinic acid and p-toluene sulfinic acid are as strong prooxidants as the aryl thiols; at high concentrations they are more active but short lived. A few other sulfur compounds or combinations had no interesting prooxidant properties. In contrast to results on polyisoprene, aryl thiols and sulfinic acids had little effect in preliminary tests in promoting the oxidation of cyclopentene and methyl-cyclohexene. The effects of a common rubber antioxidant, phenyl-β-naphthylamine, alone and in combination with various prooxidants, were followed by oxygen absorption and viscosity changes. The effects are complex; there are indications of both catalytic and anticatalytic effects, and of both scission and crosslinking. The results are most useful in showing the potential of the method for future work on understanding and comparing effects of antioxidants.

Recent Advances of Sulfonylation Reactions in Water

2020 ◽  
Vol 17 (4) ◽  
pp. 271-281
Author(s):  
Li Wu ◽  
Lifen Peng ◽  
Zhifang Hu ◽  
Yinchun Jiao ◽  
Zilong Tang
Keyword(s):  
Natural Products ◽  
Organic Synthesis ◽  
Low Cost ◽  
Point Of View ◽  
Sulfinic Acid ◽  
Sulfonyl Chlorides ◽  
Recent Advances ◽  
Water As Solvent ◽  
Proton Source ◽  
Sulfinic Acids

Background: The sulfonyl groups are general structural moieties present in agrochemicals, pharmaceuticals, and natural products. Recently, many efforts have been focused on developing efficient procedures for preparation of organic sulfones. Materials and Methods: Water, a proton source, is considered one of the most ideal and promising solvents in organic synthesis for its easy availability, low cost, nontoxic and nonflammable characteristics. From the green and sustainable point of view, more and more reactions are designed proceeding in water. Objective: The review focuses on recent advances of sulfonylation reactions proceeding in water. Sulfonylation reactions using sodium sulfinates, sulfonyl hydrazides, sulfinic acids, and sulfonyl chlorides as sulfonating agents were introduced in detail. Results and Discussion: In this review, sulfonylation reactions proceeding in water developed in recent four yields were presented. Sulfonylation reactions using water as solvent have attracted more and more attention because water is one of the most ideal and promising solvents in organic synthesis for its facile availability, low cost, nontoxic and nonflammable properties. Conclusion: Numerous sulfonating agents such as sodium sulfinates, sulfonyl hydrazides, sulfinic acid, sulfonyl chlorides and disulfides are efficient for sulfonylation reactions which proceed in water.

Kinetics and Mechanism of Oxidation of d-Penicillamine in Acidified Bromate and Aqueous Bromine

2016 ◽  
Vol 69 (11) ◽  
pp. 1305 ◽  
Author(s):  
Kudzanai Chipiso ◽  
Reuben H. Simoyi
Keyword(s):  
Sulfonic Acid ◽  
Biologically Active ◽  
Stopped Flow ◽  
Sulfinic Acid ◽  
Sulfenic Acid ◽  
Dimer Formation ◽  
Acid Product ◽  
Diffusion Controlled ◽  
Sulfinic Acids ◽  
Mechanism Of Oxidation

The oxidation of the biologically active compound d-penicillamine (Depen) by acidic bromate has been studied. The stoichiometry of the reaction is strictly 1 : 1, in which Depen is oxidized only as far as the sulfonic acid with no cleavage of the C–S bond to yield sulfate. Electrospray ionization spectroscopy shows that Depen is oxidized through addition of oxygen atoms on the sulfur centre to successively yield sulfenic and sulfinic acids before the product sulfonic acid. In conditions of excess Depen over the oxidant, sulfenic acid was not observed. Instead, nearly quantitative formation of the dimer was obtained. The dimer, which is the d-penicillamine disulfide species, was formed from a reaction of the putative highly electrophilic sulfenic acid with unreacted Depen in a condensation-type reaction and not through a radical-mediated pathway. Further oxidation of the dimer is slow because it is the most stable intermediate in the oxidation of Depen. In excess oxidant conditions, negligible dimer formation is observed. The reaction of bromine with Depen gives a stoichiometry of 3 : 1 with the same sulfonic acid product. This reaction is so fast that it is essentially diffusion controlled. Our stopped-flow instrument could not capture the oxidation by the first 2 moles of bromine, only the section of the reaction in which the sulfinic acid is oxidized to sulfonic acid.

Spectrophotometric study of the complexation equilibria of cadmium ions with 5-bromo and 5-chloro derivatives of 2-(2-pyridylazo)-5-diethylaminophenol (BrPADAP, ClPADAP)

1983 ◽  
Vol 48 (1) ◽  
pp. 52-59 ◽  
Author(s):  
Vlastimil Kubáň ◽  
Miroslav Macka
Keyword(s):  
Equilibrium Constants ◽  
Spectrophotometric Study ◽  
Graphical Analysis ◽  
Optimal Conditions ◽  
Cadmium Ions ◽  
Brij 35 ◽  
Ethanol Medium ◽  
Triton X ◽  
Derivatives Of

The composition, optical characteristics, molar absorption coefficients and equilibrium constants of the reactions of formation of the ML and ML2 complexes of both reagents with cadmium(II) ions were determined by graphical analysis and numerical interpretation of the absorbance-pH curves by the modified SQUAD-G program. Optimal conditions were proposed for the spectrophotometric determination of Cd in 10% v/v ethanol medium in the presence of 0.1% w/v Triton X-100 or 1% w/v Brij 35. BrPADAP and ClPADAP are the most sensitive spectrophotometric reagents for the determination of cadmium(II) ions (ε = 1.28-1.44 . 105 mmol-1 cm2 at 560 nm and pH 8.0-9.5) with a high colour contrast in the reaction (Δλmax ~117 nm) and a selectivity similar to that of other N-heterocyclic azodyes (PAR, PAN, etc.).

Oxidation of (1-hydroxybenzyl)ferrocene and its derivatives substituted in phenyl ring with bis(triphenylsilyl) chromate

1982 ◽  
Vol 47 (12) ◽  
pp. 3375-3380 ◽  
Author(s):  
Jaroslav Holeček ◽  
Karel Handlíř ◽  
Milan Nádvorník ◽  
Milan Vlček
Keyword(s):  
Linear Dependence ◽  
Rate Constants ◽  
Oxidation Rate ◽  
Phenyl Ring ◽  
Equilibrium Constants ◽  
Aprotic Solvents ◽  
Protonation Equilibrium ◽  
Oxidation Of Alcohols ◽  
Hammett Σ Constants ◽  
Sulphuric Acid Medium

Kinetics have been studied of oxidation of (1-hydroxybenzyl)ferrocenes substituted in phenyl ring with bis(triphenylsilyl) chromate in benzene solutions as well as protonation of these alcohols in sulphuric acid medium. Logarithms of the oxidation rate constants (kobs, 20-40 °C) and those of the protonation equilibrium constants (KR+, 25 °C) show linear dependence on the Hammett σ constants, the ρ constant values being -0.86 to -0.40 and -2.50, respectively. These negative values suggest that the both processes are influenced by the same effects and confirm the mechanism proposed earlier for oxidation of alcohols with ferrocenyl substituent by action of bis(triphenylsilyl) chromate in aprotic solvents.

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