The mechanism of acyl sulphonate reactions. Part III. The solvolyses of acyl sulphonates and sulphonic anhydrides, both cyclic and acyclic, in hydroxylic solvents, and the reaction of acetyl benzenesulphonate with a series of 3- and 4-substituted anilines

Abstract

Rate constants have been determined for the solvolyses of benzene-1,2-disulphonic, benzenesulphonic, methane-sulphonic, propane-1,3-disulphonic, ethane-1,2-disulphonic, and 3-sulphopropionic anhydrides, and of acetyl and benzoyl benzenesulphonates, in hydroxylic solvents. Selectivity between nucleophiles and the position of attack have been investigated and the Hammett ρ values have been determined for the reactions of nine m- and p-substituted anilines with acetyl benzenesulphonate in 60% and 100% dioxan. Kinetic results are discussed in terms of ring strain and changes of conformation on entering the transition state. It is concluded that the nucleophilic attack at the sulphur atom takes place via an axial displacement in a bipyramidal transition state, and that for the cyclic acyl compounds attack at the carbonyl carbon atom takes place through a distorted square-planar transition-state.