Search

The effect of mixed micelles (polyethylene glycol-CTAB cationic surfactant, shortchain alcohol-SDS anionic surfactant) on the alkaline hydrolysis of normal aliphatic esters has been studied at 20 and 30°C with the method of difference of thermogram-area of thermokinetics in this paper. The results indicate that this reaction is inhibited by the single and mixed micelles. The mixed micelles of PEG and CTAB exhibit a greater effect of inhibition on the reaction than those do in single PEG or CTAB systems. The extent of inhibition for the reaction in the mixed micelles of SDS and alcohol is less than that in single SDS micellar solutions. The critical micellar concentrations of the corresponding systems have also been measured with the conductivity method in this paper.

The kinetics of the polymerization of acrylamide in aqueous solution and CTAB micellar solution initiated by sodium sulfite has been investigated with the theory and method of thermokinetics for n order reactions with equal concentration in this paper. The influence of initiator and CTAB concetrations on molecular weight of polyacrylamide has been discussed.The second - order rate constants of this reaction at 30 and 40°C in aqueous solution are 0. 112and 0. 0262dm3 mol-1s_1, respectively. The activation energy,based on measurements at these two temperatures,is 66. -4kJ mol-1. The ratio k2√n in CTAB micellar solution is smaller than that in aqueous solution. The rate of forming radical in micellar solution has been decreased.

The alkaline hydrolysis of aspirin has been studied in CTAB micellar solution with the method of thermokinetics for the pseudo-first-order reactions in this paper. The second-order-rate constants of this reaction at 30 and 35°C in the absence of CTAB are 0. 0394 and 0. 0628 dm3 mol-1 s-1,respectively. The rates of this reaction in CTAB micellar solutions at 30 and Z5V have decreased as the increased of CTAB concentration at the considerable values of [OH-]- This reaction has been found to be inhibited by CTAB micelles.