Structure-reactivity studies of esterolysis reactions in amine carboxylate/benzene solutions

Abstract

The amine carboxylate salt system in apolar solvents provides an interesting research field from both a physical chemistry and a kinetic viewpoint. The thesis of this work is that the physical chemistry of these systems plays a major role in the observed reaction kinetics for the decomposition of p-nitrophenyl esters, but that the aggregation causes inhibition of reaction rate and not enhancement as required by the "reversed micelle" mode. Chapter One discusses the physical chemistry of these systems and reviews kinetic studies in these systems up to December 1981. Chapter Two discusses the lysis of esters in amine carboxylate systems and the revered micellar model used previously to explain the observed kinetics. The effects of temperature and of added water upon the lysis of p-nitrophenylacetate in the teramethylenediamine-bis (dodecanoate) salt system in benzene solvent are analysed by this reversed micellar model and comparison is made with the literature treatments. Chapter Three considers the reactivity of P-nitrophenylacetate in a series of related systems. The results of this study, and a Hammett study of para-substituted 4-nitrophenylbenzoates in dodecylamine propionate and teramethylenediaminebis (dodecanoate) in Chapter Four, suggest that the rate enhancement is due to a forced preassociation mechanism, and that the observed kinetic profiles are due to the aggregational behaviour of these salts in solvent benzene. Chapter Five discusses the mechanism of reaction of p-nitrophenyl esters in these systems, and Chapter Six discussed the effect of aggregation on the observed kinetics. An attached appendix tabulates 13C n.m.r. data of para-substituted 4-nitrophenylbenzoates and correlations of the chemical shift of the ring carbon atoms according to Hammett, Tsuno Yukawa, and Dual Substituent Parameter treatments. 13C n.m.r. substituent chemical shifts for the introduction of the 4-substituted benzoyl and of the 4-nitrophenoxycarbonyl groups into benzene are proposed.