Definitive evidence for a stepwise mechanism: A downward curvature in the plot of k(obs) versus amine concentrations in aminolysis reactions of dibenzo[1,2]oxathiin-6-oxide

Abstract

Pseudo-first-order rate constants (k(obs)) have been measured spectrophotometrically for aminolyses of dibenzo[1,2]oxathiin-6-oxide. The plot of k(obs) vs amine concentrations exhibits a downward curvature which levels off as the amine concentration increases. Such a downward curvature is proposed as definitive evidence for a stepwise mechanism, which is supported by the microscopic rate constants determined.