CATIONIC MICELLAR EFFECT ON THE REACTION BETWEEN DIPEPTIDE GLYCYL-ALANINE (GLY-ALA) AND NINHYDRIN WITH AND WITHOUT SALT ADDITIVES

Abstract

The effect of cationic conventional surfactants myristyltrimethylammonium bromide (TTAB),cetyltrimethylammonium bromide (CTAB), and cetylpyridinium chloride (CPC) on the interaction ofdipeptide glycyl-alanine (Gly-Ala) with ninhydrin has been studied spectrophotometrically underdifferent conditions. The reaction rates are higher in the presence of surfactants but the reaction orderremains the same in both the media (first- and fractional-order with respect to [Gly-Ala] and[ninhydrin]). Quantitative kinetic analyses of kψ[surfactant] data were performed on the basis ofpseudo-phase model of the micelles (proposed by Menger and Portnoy and developed by Bunton andRomsted) and Piszkiewicz model wherein the micellar binding constants KS for Gly-Ala and KN forninhydrin with surfactant micelles were evaluated. The catalytic efficiency in TTAB increased byadded electrolytes which had been discussed in detail.