Mechanism of Oxidation of (p‐Substituted Phenylthio)acetic Acids with N‐Bromophthalimide

Abstract

The kinetics of oxidation of (phenylthio)acetic acid (PTAA) byN-Bromophthalimide (NBP) in acetonitrile-water solvent mixture at 298 K in the presence of perchloric acid has been followed potentiometrically. The reaction is first-order each in NBP and PTAA and inverse fractional-order in H+. Also, it has been found that the reaction rate is not affected by changes in ionic strength of the reaction medium or by the addition of chemicals such as phthalimide, acrylonitrile and potassium bromide. However, an increase in the water content of the solvent mixture causes an increase in the rate of reaction. These observations have been well analyzed in favour of a SN2-type mechanism, involving NBP itself as the reactive species. Effect of substituents on the reaction rate has been analysed by employing various (p-sustituted phenylthio)acetic acids. The electron-releasing substituent in the phenyl ring of PTAA accelerates the reaction rate while the electron-withdrawing substituent retards the rate. The excellently linear Hammett plot yields a large negative ρ value, supporting the involvement a bromosulphonium ion intermediate in the rate-determining step.

Kinetics and Mechanism of Oxidation of Aniline by N-Bromophthalimide

“…has some definite advantages over other N-halo oxidants, which has been extensively used in the estimation of organic substrates 17 . A few reports of kinetics of oxidation of organic compounds such as amino acids 18 , sulfides 19,20 , hydroxy acids 21 , alcohols 22 etc., using NBP are available in the literature. However, no detailed kinetic study of oxidation of aniline with N-bromophthalimide has so far been attempted.…”

Kinetics and Mechanism of Oxidation of Methyl Phenyl Sulphide by Imidazolium Fluorochromate

“…The synthesis of sulphoxides were reported for first time by Marcker in 1865 and since then a number of methods were developed for conversion of sulphides to sulphoxides. Oxidation of organic sulphides by several oxidants such as N-halo compounds [2][3][4] , peroxo compounds 5 and chromium compounds 6 have been reported.…”

Oxidation of S-Phenylmercaptoacetic Acid by

“…The kinetics of oxidation of S-phenylmercaptoacetic acid [2][3][4][5][6][7] by various oxidants has been reported. Herein, we report the results obtained from a detailed kinetic study on the oxidation of several substituted S-phenylmercaptoacetic acids with piperidinium chlorochromate.…”