Nitroso group transfer from N-nitrososulfonamides to thiolate ions. Intrinsic reactivity

Abstract

The nitroso group transfer from N-nitrososulfonamides to thiolate ions was studied. Based on the results, the reaction rate is strongly dependent on the nature of the leaving group ( α lg ≈ − 1.30 ) , but virtually independent of the basicity of the thiol ( β nuc ≈ 0.10 ) . This dependence is ascribed to the presence of a nucleophile desolvation equilibrium ( β d ) that is followed by the attack of the thiolate ion on the nitroso group ( β nuc ′ ) via a concerted mechanism. The equilibrium constants for the loss of a nitroso group from a nitrosothiol and an N-nitrososulfonamide were used to obtain the equilibrium constants for the different reactions involved. By using rate–equilibrium correlations, the parameters α lg norm , β d , and β nuc ′ norm were obtained.