The liquid-liquid phase transfer catalyzed reaction of benzyl chloride with aqueous ammonium sulfide is modeled based on interfacial mechanism considering the reaction kinetics in the organic phase and ionic equilibrium in the aqueous phase. The rate constants and equilibrium constants of the developed model are estimated at different temperatures using an indigenously developed algorithm based on Levenberg-Marquardt. The frequency factors and activation energies of the rate constants are determined from an Arrhenius plot of ln (rate constants) versus 1/T. The calculated results based on the developed model using the estimated reaction parameters are compared with the experimental observations, and quite a good correlation is observed.

Intensification of slow heterogeneous reactions involving an organic substrate and an ionic reactant present either in aqueous phase (liquid-liquid) or solid phase (solid-liquid) by Phase Transfer Catalysts (PTC) is nowadays an attractive technique for organic synthesis because of its inherent advantages of enhanced reaction rates, selectivity and mild operating conditions (Dehmlow and Dehmlow, 1983). Although much effort has been devoted to the synthesis of organic chemicals, very little work was done in the past on the modeling of the liquid-liquid phase transfer catalyzed reactions of commercial importance.

The modeling of the dynamic behavior of liquid-liquid phase transfer catalysis is quite complex and involves the consideration of reactions in both aqueous and organic phases, and mass transfer of catalyst and active catalysts between the phases. The dynamic behavior of liquid-liquid phase transfer catalyzed reactions was first reported by Wang and Yang based on two-film theory of mass transfer and pseudo-steady-state hypothesis (Wang and Yang, 1991). Further, kinetic model was developed taking into account the interphase mass-transfer resistance of active catalysts and without considering the extractive equilibrium of the active catalysts in one of the phases (Bhattacharya and Mungikar, 2002). The kinetic model was also developed considering the effect of changes in electrolyte composition in the aqueous phase and separate contributions of PTC-enhanced reactions and non-PTC reactions (Satrio and Doraiswamy, 2002). However, no mathematical model was developed in the past considering the complex ionic equilibrium in the aqueous phase based on a thermodynamic framework.

Chemical Engineering Journal, Modeling, Liquid-liquid Phase Transfer Catalysis, Interfacial Mechanism, Hydrogen Sulfide, Dibenzyl Sulfide, Phase Transfer Catalysts, PTC, Benzyl Chloride, BC, Dibenzyl Sulfide, DBS, Benzyl Mercaptan, BM, Conventional Process, Aqueous Ammonium Sulfide.