Kinetic medium isotope effect in nucleophilic substitution

Abstract

Kinetics of various kinds of nucleophilic substitution were studied in ethanol and in [hydroxy-²H₁]ethanol in order to evaluate the rate ratios due to pure medium effects. The values of k_EtOD/k_EtOH were 1·84 and 1·83 for substitution of 1-chloro-2,4-dinitrobenzene and of 1-chloro-2,2-di-(p-nitrophenyl)ethylene, respectively, by ethoxide ion at 25°; 1·30 for substitution of 1-chloro-2,4-dinitrobenzene by pyridine at 90°; 1·3–1·4 for substitution, and 1·7–1·8 for elimination, in the concurrent reactions of n-butyl chloride with ethoxide ion at 60–80°.