Hydrolysis of aryl N-methyl-N-arylsulfonylcarbamates

Abstract

Tertiary sulfonylcarbamates 1 were prepared by reaction of a sulfonamide anion with aryl chloroformates. These previously unreported compounds hydrolyse in aqueous media to the parent sulfonamide and phenol. The pH–rate profile shows both spontaneous and base-catalysed processes. The reaction is also catalysed by buffers. Kinetic data for the hydrolysis of these compounds by HO⁻ are best interpreted in terms of a mechanism involving rate-limiting formation of a tetrahedral intermediate from nucleophilic attack of hydroxide ion at the carbamate carbonyl carbon atom. For the 4-nitrophenylsulfonyl compound 1h decomposition of the tetrahedral intermediate appears to be rate-limiting with the sulfonamide anion, rather than the phenoxide, functioning as the leaving group. The buffer-catalysed process is consistent with general base-catalysed attack of water at the carbamate carbonyl carbon atom.