Synthesis and characterization of cationic quaternary ammonium geminis (16–s–16) and their role in ninhydrin–[Cu(II)–His]+ reaction

Abstract

Cationic quaternary ammonium gemini surfactants were synthesized by mixing N,N-dimethylcetylamine and α,ω-dibromoalkane. The synthesized products were characterized by C, H, N elemental and 1H NMR analyses. The critical micelle concentration (CMC) of these surfactants with and without additives was calculated by means of the conductivity technique. The role of the synthesized quaternary ammonium geminis in the reaction was investigated by a UV–vis spectroscopy. The rate constant (kψ ) was determined at different gemini concentrations and plotted graphically as kψ vs. [16–s–16]. Additionally, the influence of other reaction parameters (viz., reactants, pH, and temperature) was investigated. The binding constants were also determined (K A for [Cu(II)–His]+ and K B for ninhydrin). The resulting kψ –[16–s–16] plot can be understood in terms of a pseudo-phase model of micelles.