ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 34, Number 6
JKCSEZ 34(6)
December 20, 1990 

Dephosphorylation of p-nitrophenyldiphenylphosphate(p-NPDPP) mediated by anions of sodium 2-alkylbenzimidazole-5-sulfonate(R-BI-SO3Na) in CTABr micellar solutions are obviously slower than that by anion of sodium benzimidazole-5-sulfonate(BI-SO3Na), and the reation rates were decreased with increase of lengths of alkyl groups. This presents a striking contrast to the reactions in aqueous solutions without added CTABr, of which the reaction rates are on approximately same levels. It seems due to steric effect of alkyl groups of R-BI-SO3Na in the Stern layer of micelle, and it is supported by measured activation parameters(△H≠, △G≠ and △S≠) of the reactions in aqueous and micellar solutions. In addition to nucleophilic ability of benzimidazole moiety of R-BI-SO3Na on the reactions, these compounds with long alkyl groups(nonyl to pentadecyl) are micellized for themseleves, and increase the reaction rates due to their micellar catalyses in aqueous solutions, not including CTABr.