Hydrolysis of aryl N-methyl-N-arylsulfonylcarbamates

Tertiary sulfonylcarbamates 1 were prepared by reaction of a sulfonamide an ion with aryl chloroformates. These previously unreported compounds hydroly se in aqueous media to the parent sulfonamide and phenol. The pH-rate profi le shows both spontaneous and base-catalysed processes. The reaction is als o 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 hydrox ide ion at the carbamate carbonyl carbon atom. For the 4-nitrophenylsulfony l compound Ih decomposition of the tetrahedral intermediate appears to be r ate-limiting with the sulfonamide anion, rather than the phenoxide, functio ning as the leaving group. The buffer-catalysed process is consistent with general base-catalysed attack of water at the carbamate carbonyl carbon ato m.