Kinetics of reaction of oximate α-nucleophiles with p-nitrophenyl acetate in alkyltriphenyl phosphonium bromide micelles

Rate constants for the nucleophilic hydrolysis of p-nitrophenyl acetate by the butane 2,3-dione monoximate ion at pH 7.9 and 27 degrees C have been measured kinetically in alkyltriphenylphosphonium (C-12-, C-14-, C-16-) bromide micellar media. Addition of surfactants led to a significant increase in the pseudo-first order rate constants. The rate-surfactant profiles are fitted quantitatively in terms of pseudo phase ion exchange model. There is a decrease in the observed rate with decreasing hydrophobic chain length for the same surfactant head group. cetyltriphenylphosphonium bromide is more reactive than cetyltrimethylammonium bromide.