The reactivity of p-nitrophenyl esters with surfactants in apolar solvents. VII. Substituent effects on the reactivity of 4'-nitrophenyl 4-substituted benzoates in benzene solutions of dodecylammonium propionate and butane-1,4-diamine bis(dodecanoate)

The rate of decomposition of a series of 4'-nitrophenyl 4-substituted benzoates has been measured at 341 K in benzene solutions of dodecylammonium propionate and butane-1,4-diamine bis-(dodecanoate). The bimolecular rate constant due to general acid-general base catalysis from the head-group components of the surfactants is dependent on the nature of the substituents, and the rate data have been correlated by Hammett σ and σ+, Tsuno-Yukawa, and Taft dual substituent parameter linear free energy relationships. The reactivity of the esters has also been compared with the 13C n.m.r. chemical shift of their carbonyl carbon atoms. The results are consistent with a mechanism involving a general-acid-catalysed aminolysis of the unprotonated ester.