- Kinetics and Mechanism of the Reaction between Thymol Blue and Bromate in Acidic Medium
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The reaction between Thymol Blue (TB) and bromate in the presence of sulfuric acid has been studied by monitoring the depletion kinetics of TB.The reaction exhibits complex kinetic behaviour.Under excess bromate and acid conditions, the reaction was initially fast and was followed by a kinetically controlled slow reaction.After an induction period, the reductant again underwent a rapid depletion.The kinetic data were analysed by determining the reaction rates under the two rapid depletion conditions and by estimating the induction time between the two rapid depletion stages.Under the initial conditions the rate-limiting step was found to be first order with respect to H(1+), bromate and TB.The overall potential of the reaction increased continuously with the progress of the reaction.The concentration of bromide dropped initially and built up slowly reaching a maximum before decreasing rapidly with corresponding fast depletion of Thymol Blue.At low bromate concentration TB reacted with bromate with stoichiometric ratio of 3:2, but with excess bromate the ratio increased to 4:5.The kinetics of the reaction between Thymol Blue and aqueous bromine were monitored by a stopped-flow technique.The probable reaction mechanism with bromide acting as an autocatalyst is discussed.
- Jonnalagadda, S. B.,Chinake, C.,Simoyi, R. H.
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- Correlation of the rates of Solvolysis of 2,1-benzoxathiol-3-one-1, 1-dioxide (2-sulfobenzoic acid cyclic anhydride)
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Solvolysis of acyclic mixed carboxylic-sulfonic anhydrides in hydroxylic solvents is known to involve displacement at the carbonyl carbon to produce a carboxylic acid (water as the nucleophile) and/or an ester (alcohol as the nucleophile) plus the anion of the sulfonic acid. Parallel solvolyses of the cyclic mixed anhydride 2-sulfobenzoic anhydride (structurally similar to phthalic anhydride but with one carbonyl group replaced by a sulfonyl group) involve expulsion from the carbonyl carbon of a sulfonate anion that remains attached as an orthosubstituent in the benzoic acid and/or benzoate ester produced. This complicates the choice of a solvent-ionising-power scale for use in an extended Grunwald-Winstein equation treatment. The YOTs scale, previously recommended as a good general purpose scale, is chosen and used in conjunction with the NT solvent nucleophilicity scale. An acceptable correlation is obtained, which is improved when the two solvents rich in the highly ionising 1,1,1,3,3,3-hexafluoro-2-propanol are excluded. As the solvent is varied, the sensitivities to the changes induced in the two scales are low, consistent with an early transition state, but their ratio has a value which is typical for a pathway involving addition-elimination, with addition rate-determining. Earlier reports, supporting aspects of the proposed mechanism, are reviewed.
- Kevill, Dennis N.,Ryu, Zoon Ha
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p. 561 - 566
(2015/11/27)
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- Saccharin reaction with cyanide
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A novel reaction between saccharin (1,2-benzisothiazole-3(2H)-one-1,1- dioxide, o-sulfobenzimide, or obenzoic sulfimide) and cyanide to afford an unexpected compound, 2-(cyanosulfonyl)benzamide, has been described. Cyanide ion proved to attack the sulfonyl group of o-sulfobenzimide over 170°C to open the ring and to add to form a new C-S bond. This is an unexpected reaction, as the leading theory of chemical reaction predicts cyanide to be too weak to react with sulfonyl groups. The spectroscopic data and the elemental analyses confirm the structure of the resulted compound and support the mechanism of reaction. The reaction pathway is important from the theoretical point of view, however it might serve both preparative and analytical purposes.
- Drochioiu, Gabi,Deleanu, Calin,Rusu, Elena,Mangalagiu, Ionel
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experimental part
p. 315 - 319
(2012/06/01)
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- Synthesis of a few cyclothiadiazanones and aminosulfonyl benzamides from saccharin
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Saccharin is hydrolyzed with two different acids to yield 1,2-di-acid. The di-acid, on chlorination with phosphorous pentachloride, gave 2-chlorosulfonylbenzoyl chloride. The 2-chlorosulfonylbenzoyl chloride on hydrazinolysis gave benzothiadiazinetrione, while with phenyl hydrazine it selectively yielded 2-phenylbenzothiadiazinetrione. 2-chlorosulfonoylbenzoyl chloride with different aromatic 1,2- diamines resulted in dibenzothiadiazocine derivatives. Electron-donating groups in the diamine facilitate while the electron-withdrawing groups retard the cyclization. However, aliphatic diamines, aniline and substituted anilines readily gave acyclic aminosulfonyl carboxybenzamides on condensation with 2- chlorosulfonylbenzoyl chloride. The di-acid and anhydride did not react with either hydrazine/phenyl hydrazine or amines to give the above products. However, when its ester derivative, isopropyl-2- chlorosulfonylbenzoate, condensed with hydrazine, it gave benzothiadiazinetrione. But the ester failed to react with phenyl hydrazine. All the condensation reactions were carried out at room temperature.
- Ramana, P. Venkata,Reddy, A. Ram
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experimental part
p. 71 - 81
(2010/10/04)
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- Process for the preparation of aromatic O-sulfocarboxylic acids and sulfonylureas
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The invention relates to a process for the prepn of ortho-sulfocarboxylic acids, which comprises: a) in a first reaction step, diazotizing an aromatic o-aminosulfonic acid in the presence of an acid and nitrite in water, in an organic solvent or in a mixture thereof, to an o-diazonium sulfonate, and, b) in a second reaction step, reacting the o-diazonium sulfonate in the presence of a palladium catalyst in water, in an organic solvent or in a mixture thereof, with carbon monoxide, under overpressure, to an aromatic o-sulfocarboxylic acid. The invention also relates to a process for the preparation of sulfonylureas using o-sulfocarboxylic acids as intermediates. Thus, 4-methoxyaniline-2-sulfonic acid was diazotized and treated with CO to give 97% 4-methoxybenzoic acid 2-sulfonic acid.
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- Acid-catalyzed hydrolysis of benzenesulfonamides. Rate enhancements by ortho-alkyl substituents
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Pseudo-first-order rate constants have been measured for the acid-catalyzed hydrolysis of a series of N,N-dimethyl- and N-methyl-N-phenylbenzenesulfonamides in 70 percent (v/v) CF3CO2H/H2O at 99 deg C.Analysis of the effect of the alkyl substituents in the benzene ring shows a remarkable rate enhancement by ortho-alkyl groups, in the contrast with a rate retardation of similar substituents in the corresponding benzamides.The rate enhancement in the sulfonamides is attributed to relief of initalstate strain in the transition state for hydrolysis.When the sulfonamide moiety is contained in a five-membered ring fused to a phenyl ring, the rate of hydrolysis is markedly reduced by an ortho-methyl substituent.
- Wagenaar, Anno,Kirby, Anthony J.,Engberts, Jan B. F. N.
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p. 203 - 205
(2007/10/02)
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- INTRAMOLECULAR SULFONAMIDE-CARBOXAMIDE REARRANGEMENT.
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Several o-carboxy-N,N-dialkylbenzenesulfonamides rearrange intramolecularly to o-chlorosulfonyl-N,N-dialkylbenzamides upon treatment with an excess of thionyl chloride in an apolar solvent.
- Hovius, Klaas,Wagenaar, Anno,Engberts, Jan B. F. N.
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p. 3137 - 3140
(2007/10/02)
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- EFFECT OF STRUCTURE ON THE KINETICS AND MECHANISM OF THE ACID-CATALYZED DECOMPOSITION OF N-NITROBENZENESULFONAMIDES
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The decomposition rate of a series of ring-substituted N-nitrobenzenesulfonamides in aqueous sulfuric acid was measure by a spectrophotometric method.Decomposition of the compounds takes place both by the cleavage of the N-S bond to form the corresponding sulfonic acid, nitrous oxide, and water and by denitration.In crease in the electronegativity of the substituent in the aromatic ring promotes the denitration reaction.
- Drozdova, O. A.,Astrat'ev, A. A.,Kuznetsov, L. L.,Selivanov, V. F.
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p. 2063 - 2067
(2007/10/02)
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- Process for producing saccharin
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1,2-Benzoisothiazole-3-on-1, 1-dioxide having the formula STR1 wherein X represents hydrogen, halogen, nitro, lower alkyl or lower alkoxy and Y represents hydrogen, halogen, lower alkyl, or lower alkoxy is prepared by reacting phosgene with an o-sulfobenzoic acid compound having the formula: STR2 or an alkali metal salt or alkaline earth metal salt thereof in the presence of dimethylformamide, thereby producing a mixture of a dichlorotolylsultone and a chlorosulfonylbenzoylchloride; (b) reacting the reaction products of step (a) with an alcohol of the formula ROH wherein R represents a lower alkyl group; and then (c) reacting the product of step (b) with ammonia.
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