Abstract
•Results favor to association of premicelle/micelle between the reactants and surfactant.•Optimum situations are obtained in geminis by studying impact of several factors on rate.•A decent matching of rates (kψ and kψcal) approves applicability of pseudo-phase model.
Herein, catalytic impact of aqueous-micellar solution of twin headed 16-s-16 (s = spacer) gemini surfactants (GS) was measured in the study of ninhydrin (nin) with Aspartic (Asp) amino acid. The study was performed over the different range of reactants’ concentration, temperature and pH. Reaction obeyed the order to be respective fractional and unity in [nin] and [Asp]. The values of several quantities, viz., critical micellar concentration (cmc), thermodynamic parameters, and binding parameters were calculated and described herewith. The experimental outcomes depict that the reaction is catalyzed, significantly, by twin headed gemini surfactants and follow the order at all concentration as: GS-4 > GS-5 > GS-6. In the rate constant (kψ) vs. [GS] rate profiles, kψ intensifies even at below cmc values of surfactants (region I), and previously observe practically unchanged behavior (region II). Finally, a fast changes in kψ is detected (region III). Catalytic impact of twin headed GS achieved in this study is deduced by using a model called as micellar pseudo-phase in which rate constant depends on both the reactants. The numerous kinetic constants in twin headed geminis were evaluated and elaborated. An acceptable mechanism reliable with kinetics comprising the development of Ruhemanns’ purple between nin and Asp has been proposed.