Reactivity of vinyl sulphonic esters. Part XIII. Pronounced anchimeric assistance in the solvolysis of dialkyl-β-alkyl(or aryl)thiovinyl sulphonates

Abstract

trans-1,2-Dimethyl-2-methylthiovinyl 2,4,6-trinitrobenzenesulphonate reacts ca. 4 × 10⁴ times faster than tri-methylvinyl 2,4,6-trinitrobenzenesulphonate in 9 : 1 nitromethane–methanol at 25°. These and other kinetic data on the solvolysis of a number of 1,2-dimethyl- and 1,2-di-n-propyl-β-alkyl(or aryl)thiovinyl sulphonates are taken as evidence of effective anchimeric assistance by the β-sulphur atom and of the intermediacy of thiirenium ions.