Nuclear magnetic resonance investigations of iminium ion intermediates. Part 10. Multinuclear and kinetic study of the reaction between Lewis acids and ureas

Abstract

The structure of the intermediate and the mechanism of the reaction between ureas (tetramethyl- or tetrabutyl-ureas) and Lewis acids (COCl₂ or POCl₃) have been studied by structural and dynamic n.m.r. The values obtained for the rate constants are discussed in terms of solvent and structural effects and the activation parameters are presented in the formalism of enthalpy–entropy compensation.