Kinetics and mechanism of the aminolysis of phenyl substituted phenyl chlorophosphates with anilines in acetonitrile

Abstract

The kinetics and mechanism of the aminolysis of phenyl substituted phenyl chlorophosphates with anilines are investigated in acetonitrile at 55.0 °C. Very sensitive variation of ρ_Y (δρ_Y  0) with the change of substituent on the nucleophile (δσ_X) leads to a large negative cross-interaction constant, ρ_XY = (δρ_Y)/(δσ_X) = –1.31. The secondary kinetic isotope effects observed with deuterated aniline nucleophiles are of the inverse type (k_H/k_D = 0.61–0.87), and small ΔH ^‡ (1.6–9.7 kcal mol^–1) and large negative ΔS ^‡ (–43 to –65 e.u.) values are obtained. These results are consistent with a concerted process with a late, product-like transition state in which both bond making and leaving group departure are extensive.