Dipeptide Glycyl-Glycine (Gly-Gly)–Ninhydrin Reaction: Effect of Alkanediyl-α,ω-bis(dimethylcetylammonium bromide) (16-s-16, s = 4, 5, 6) Gemini Surfactants on the Reaction Rate

The present work concerns with the effect of alkanediyl-α,ω-bis(dimethylcetylammonium bromide) gemini surfactants on the reaction rate of ninhydrin with glycyl-glycine. The spectra showed peaks at 400 nm and 570 nm in aqueous and aqueous–micellar media indicating the formation of the same product. Under pseudo-first-order conditions of excess ninhydrin, the reaction followed an irreversible first- and fractional-order kinetics with respect to [Gly-Gly] and [ninhydrin]. Also, the rate constants (kψ) increases and leveling-off regions are found with [geminis] (akin to conventional cetyltrimethylammonium bromide, CTAB), a third-region of increasing kψ is observed at higher [geminis]. The kinetic data in gemini micellar medium have been examined with the pseudo-phase model.