ZINC DIPEPTIDE COMPLEX ([ZN(II)-GLY-TYR]+)–NINHYDRIN REACTION IN PRESENCE OF GEMINI SURFACTANTS: A KINETIC STUDY

Abstract

Kinetics of the title reaction has been carried out by studying the reaction spectrophotometrically at 80 ºC and pH 5.0 in presence of cationic gemini (alkanediyl-α, ω- bis(dimethylhexadecylammonium bromide)) surfactants. The reaction followed first-order kinetics in [Zn(II)-Gly-Tyr]T + complex and fractional-order kinetics in [ninhydrin]T. Typical rate constant (kΨ) increase and leveling-off regions (like conventional monomeric surfactants, e.g., CTAB) are found with gemini surfactants. Additionally, the gemini surfactants also produced a third region of increasing kΨ at higher concentrations. The data are interpreted in terms of pseudo-phase model (assuming the association/incorporation of both the reactants at the micellar surface).