Didodecyldimethylammonium Chloride Research Articles

Deprotonation of 5-nitroindole and its 2-carboxylate ion in twin-tailed surfactants

Deprotonations of 5-nitroindole (1) and its 2-carboxylate ion (2) at high pH are increased by selfassemblies of didodecyldimethylammonium chloride and hydroxide (DDDACl and DDDAOH). The increased deprotonation can be accounted for quantitatively in terms of binding of OH– and the indicatiors to the colloidal self-assemblies. Basicity constants in the self-assemblies are similar to those in micelles of cetyltrimethylammonium chloride, bromide, and hydroxide (CTACl, CTABr, and CTAOH) and are slightly smaller than in water.

Effect of ionic surfactants on aminolysis of p-Nitrophenyl acetate by imidazoles in carbon tetrachloride

The pseudo-first order rate constant for the decomposition of p-nitrophenyl acetate in carbon tetrachloride was measured as a function of the concentration of imidazole and 2-alkylimidazoles solubilized by didodecyldimethylammonium chloride (DDAC) or bromide (DDAB) and dio(2ethylhexyl) sodium sulfosuccinate (AOT). The rate constants in the pure solvent and in the presence of surfactants were obtained from the slopes of straight lines over the lower concentration range of imidazole and 2-alkylimidazoles. It was observed that the addition of the surfactants to the reaction system increases the rate constants by several times over those in the pure solvent. The magnitude of the rate enhancement was of the order: DDAC > DDAB > AOT for the imidazole in the surfactant systems and imidazole > 2-undecylimidazole > 2-isopropylimidazole in the DDAB systems. The surfactant effect could be elucidated in terms of strength of the interaction between the surfactants and imidazole or 2-alkylimidazoles obtained from NMR and vapor pressure osmometry.

Mechanism of solubilization of water by oil-soluble surfactant solutions II. Cationic surfactants

The vapor pressure of water solubilized by didodecyldimethyl ammonium chloride, bromide, or iodide in benzene or tetrachlorethylene and its temperature dependence were measured. The limiting amount of water solubilized ( S 0) and the heat of solubilization ( ΔH S ) were obtained from the measurement. The micellar weight ( M) of these surfactants was also measured. The order of magnitude of S 0, ΔH S , and M was chloride > bromide > iodide. Solubilization of water is partly explained by the ion-dipole interaction between the water molecule and the halogen anion, but the acid-base interaction also needs to be taken into consideration.