The study of the influence of surfactant charge on alkaline hydrolysis reactions of acetylsalicylic acid (ASA) and triflusal (TFL) using spectrophotometric methods

Kinetics and Mechanism of Alkaline Hydrolysis of N-(o-Aminophenyl)Phthalimide in the Presence and Absence of Cationic Micelles and Sodium Salts of Aliphatic Acids

Pseudo first-order rate constants, k obs, for the alkaline hydrolysis of N-( o-aminophenyl) phthalimide, obtained at constant [CTABr]T (total concentration of cetyltrimethylammonium bromide) and varying concentrations of inert salt MX (MX = sodium formate, sodium acetate, sodium propanoate, sodium butyrate, sodium valerate and sodium hexanoate) follow the relationship: [Formula: see text], where θ and KX/S are empirical constants and S = HO-. The values of KX/S for each aliphatic acid decrease with an increase in [CTABr]T. This relationship gives an empirical constant whose magnitude is the measure of the ability of an ion, X-, to expel another counterion S-, from the cationic micellar surface to the bulk aqueous phase. The values of the empirical constant, KX/S, are used to derive the ion exchange constant, KBrX.

Captopril as a nucleophile for ester cleavage. Formation of the thiolester S-benzoylcaptopril

The reaction between captopril and phenylbenzoate yields S-benzoylcaptopril that is very stable in a carbonate buffer or in an aqueous micellar medium.

Acid Hydrolysis of Bromazepam Catalyzed by Micelles, Reverse Micelles, and Microemulsions

Kinetics of the acid hydrolysis of bromazepam (Bz) has been investigated in micelles, reverse micelles, and microemulcions of cetyltrimethylammonium bromide (CTAB) by spectrophotometric method. The rate of the acid hydrolysis of Bz was found to be enhanced both below and above the critical micelle concentration (CMC) of CTAB in aqueous solution. The pseudo-first-order rate constant (k′) shows an initial decrease for both low and high H+concentrations. With further increase in [CTAB], at low [H+], thek′attains an almost constant value, while, at high [H+], thek′passes through a maximum and then decreases. The kinetic data for catalysis by micelles of CTAB was interpreted with the pseudophase ion exchange (PIE) model. In CTAB/cyclohexane/1-butanol/water microemulsions, as the water to surfactant ratio (wo) increases, the physicochemical properties and droplet sizes of microemulsions significantly change and distinct changes in reaction environment can be marked. The rate of the hydrolysis reaction exhibits excellent correlation with the physicochemical properties and droplet sizes of the microemulsions and reverse micelles of CTAB. At [H+] = 0.001 M, in reverse micelles and microemulsions of CTAB, thek′of the acid hydrolysis of Bz decreases sharply followed by a slight increase with increasingwo.