Effect of Quaternary Ammonium Gemini Surfactant Solution on the Rate Constant of the Ninhydrin-Lysine Reaction

The effect of solutions of double-chained quaternary ammonium gemini surfactants (16-s-16, s = 4-6) was characterized on the rate constant of the ninhydrin (nin) and lysine (Lys) reaction using a ultraviolet-visible (UV-vis) spectrophotometer. Rate constant (k(psi)) values were obtained at different geminis. However, k(psi) values obtained at several geminis were displayed in the form of the k(psi)-[gemini] rate profile, and the quantitative estimation of these results was elucidated employing a model of micellar catalysis referred to as pseudophase. The role of other experimental ingredients such as nin, Lys, pH, and temperature (T) was examined in geminis, and k(psi) values as a function of these parameters were determined. Data treatment confirms a fractional order in [nin] and a unity order in [Lys]. Using conductometric evaluation, the critical micellar concentration (cmc) of pure double-chained gemini surfactants (16-6-16, 16-5-16, and 16-4-16) and presence of nin and Lys were recorded. Results of the present experimental value were used to determine micellar binding constants (K-A for Lys and K-B for nin). The binding constants and second-order rate (k(m)) affect the solvent properties at the micellar surface and hence are taken into consideration and discussed.