Author: M. R. Aruna Kumari, P. Shyamala, D. H. Puranam, K. V. Nagalakshmi, B. Leela Kumari

DOI: http://doi.org/10.31788/RJC.2026.1949647

The kinetics of the nucleophilic deacylation of p-nitrophenyl acetate by triethanolamine were investigatedinaqueous medium, single-surfactant systems containing sodium dodecyl sulphate (SDS) or Triton X-100 (TX-100), and binary SDS–TX-100 mixed micelles to elucidate the effect of micellar composition on reaction kinetics. Reaction progress was monitored spectrophotometrically under pseudo-first-order conditions by followingtheformation of p-nitrophenolate at 400 nm. Both surfactants enhanced the reaction rate compared with water, withTX- 100 exhibiting greater catalytic efficiency. Mixed SDS–TX-100 micelles produced the highest rate enhancement because of synergistic electrostatic and hydrophobic interactions. Regular Solution Theory was applied to evaluatethe interaction parameter (β) and the composition-dependent critical micelle concentrations, confirming non-ideal mixed-micelle behaviour. The results demonstrate that mixed micelles provide a tunable reaction microenvironment with superior catalytic performance compared with single-surfactant systems. This study advances the understandingof surfactant-mediated catalysis and provides useful insights for designing efficient aqueous catalytic systems.

Keywords: Micellar Catalysis, Ester Deacylation, Mixed Surfactant Systems, Regular Solution Theory, ReactionKinetics, Sodium Dodecyl Sulphate, Triton X-100