Experimental validation of equilibrium based mathematical modelling of liquid‐liquid phase transfer catalysis

Abstract

The reaction between two compounds which reside in immiscible phases can be accelerated using a phase transfer catalyst. The catalyst helps to transfer a species ion from one phase to the other phase, thus promoting its reaction. Several mechanisms have been proposed to describe phase transfer catalyzed reactions. In this work, we have carried out an experimental and theoretical study of phase transfer catalysis in batch mode. A mathematical model is developed which helps to predict the progress of the reaction under different operating conditions. Here the different species in the aqueous phase are assumed to be in equilibrium and these react with the species in the organic phase. The effect of diffusional resistance inside the dispersed organic phase is shown to be negligible. The two reaction systems studied are the phase transfer catalyzed (i) thioetherification and (ii) benzyl alcohol oxidation using sodium hypochlorite. Batch experiments were performed to determine the effect of catalyst loading, solvent dilution, and pH. The experimental results show that with an increase in catalyst loading, the phase transfer catalyzed reactions were accelerated. The use of a minimal amount of solvent results in a better performance. Benzyl alcohol oxidation is favoured under low pH conditions. The developed model is able to capture the performance of the system over a wide range of operating conditions accurately.