Effects of Surfactants on Solvolysis of p-Nitrophenyl Alkanoates Catalyzed by 4-(Dialkylamino)pyridine-Functionalized Polymer in Aqueous Methanol Solution

Catalysis of the solvolysis of p -nitrophenyl alkanoates 2 ( n = 2−18) by 4-(dialkylamino)pyridine-functionalized polymer 1 in the presence of sodium n -dodecyl sulfate (SDS), n -dodecyltrimethylammonium bromide (DTAB), and heptaethylene glycol n -dodecyl ether (HEGDE) was investigated in 50:50 (v/v) methanol−water buffer (0.05 M H 2 PO 4 - /HPO 4 2 -, pH 8.0) solution. Strikingly, a large rate enhancement is observed in the presence of anionic surfactant SDS for the solvolysis of 2 ( n = 10−18) as compared with the corresponding reaction catalyzed by 1 or SDS alone. SDS is believed to bind both substrate and catalyst within micellar aggregates and influence reactivity by a combination of catalyst−substrate proximity and micellar microenvironment. In the presence of HEGDE, no significant effects on the 1 -catalyzed solvolysis of 2 ( n < 8) were observed. At (2.5−7.5) × 10 - 5 unit mol L - 1 1, the solvolysis rate exhibits a modest decrease for 2 ( n = 10 and 12) and a modest increase for 2 ( n = 14, 16, and 18) with added nonionic surfactant HEGDE. The solvolysis rate for 1 -catalyzed solvolysis of 2 ( n = 2−18) was found to be unchanged by cationic surfactant DTAB in aqueous methanol solution.