Unusual Catalytic Activity of Anionic Surfactant Analogues of 4-(Dimethylamino)Pyridine in Carboxylate Ester Hydrolyses

Abstract

Anionic surfactants containing the 4-(N,N-dialkylamino)pyridine moiety and incorporating sulfate (2), phosphate (3), sulfonate (5), and carboxylate (7) end groups were synthesized and tested as catalysts for the hydrolysis of 4-nitrophenyl hexanoate (PNPH). Surfactant 2 was the most active, with k2 = 38.0 M-1 s-1 in the absence of added CTAC and 62.2 M-1 s-1 in 0.001 M CTAC. The other derivatives tested (3 and 7) were still twice as active as neutral, cationic, and zwitterionic surfactants of the same type. Possible reasons for these rate enhancements are discussed. © 1988, American Chemical Society. All rights reserved.