A test of Leffler's assumption for a simple addition reaction in aqueous solution

Abstract

Substituent effects for the N- and O-aryl groups on rate and equilibrium constants for the system ArO^–+ Ar′NCS⇌ ArOCSAr′ in aqueous solution lead to identical Leffler–Grunwald parameters (α=β_F/β_EQ) despite the marked difference in the individual β values; the α-parameter is therefore a good measure of transition-state structure for the reaction.