Hydrolyses of dianionic 2,4-dinitrophenyl phosphate, substituted at position 5 by Me, OMe, n-OC14H29 (DNMePP2-, DNMeOPP2-, and DNTDOPP2- respectively) are accelerated by cationic micelles of cetyl trialkylammonium bromide (CTABr, CTPABr, and CTBABr, with alkyl ) Me, n-Pr, and n-Bu, respectively). There are well-defined rate maxima in dilute surfactant, below the critical micelle concentration, for reaction of DNTDOPP2- in the sequence CTBABr > CTPABr > CTABr, because of acceleration by premicelles which is not observed with the methoxy and unsubstituted derivatives. The rate maxima disappear as these species “dissolve” in micelles at higher surfactant concentrations.
Hydrolyses of Dinitroalkoxyphenyl Phosphates in Aqueous Cationic Micelles. Acceleration by Premicelles
BRINCHI, Lucia;DI PROFIO, Pietro;GERMANI, Raimondo;SAVELLI, Gianfranco;
2000
Abstract
Hydrolyses of dianionic 2,4-dinitrophenyl phosphate, substituted at position 5 by Me, OMe, n-OC14H29 (DNMePP2-, DNMeOPP2-, and DNTDOPP2- respectively) are accelerated by cationic micelles of cetyl trialkylammonium bromide (CTABr, CTPABr, and CTBABr, with alkyl ) Me, n-Pr, and n-Bu, respectively). There are well-defined rate maxima in dilute surfactant, below the critical micelle concentration, for reaction of DNTDOPP2- in the sequence CTBABr > CTPABr > CTABr, because of acceleration by premicelles which is not observed with the methoxy and unsubstituted derivatives. The rate maxima disappear as these species “dissolve” in micelles at higher surfactant concentrations.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
