The Micelle-promoted Selective Hydrolysis of Anionic and Nonionic Ester Substrates by Hydroxamic Acids and Histidine Derivatives

Abstract

Abstract The hydrolyses of anionic 3-nitro-4-acyloxybenzoic acid (S2−–S16−) and nonionic p-nitrophenyl carboxylate (S2–S16) substrates catalyzed by hydroxamic acids (C6–C12) and histidine derivatives (AcetHis and LauHis) were performed with and without alkyltrimethylammonium (DTAC, CTAB, and OTAC) surfactants at pH 7.45. The present reaction was characterized by the selectively efficient hydrolysis of the same substrate of S6− or S10 by the comicellar Cm (m=8, 10, or 12)–CTAB (or OTAC) or LauHis–CTAB (or OTAC) catalysts. Relevant factors to such a selective hydrolysis of a specific substrate by the comicellar catalysts were discussed by taking notice of the electrostatic-charge-attraction force, steric hindrance, and hydrophobic interaction. The investigation of the binding constants in the present micellar reaction system demonstrated the importance of an appropriate hydrophobic interaction between a substrate and micelles for the selective rate enhacement of ester-hydrolysis.