Dynamics of the Reaction of 2,4,6-tribromophenol and Benzyl Bromide by Phase Transfer Catalysis.

Abstract

The dynamics of the alkylation of 2,4,6-tribromophenol in an alkaline solution of KOH/chlorobenzene solvent by phase transfer catalysis was simulated using the two-film theory, taking account of mass transfer and distribution of catalysts between the two phases as well as the intrinsic reaction kinetics in both the organic and aqueous phases. Independent experiments were designed to obtain the distribution coefficients and the overall mass transfer coefficients of the catalysts between the two phases. The organic-phase intrinsic reaction-rate constant was obtained by carrying out the half-organic phase reaction. Without adding benzyl bromide, a reaction was also conducted to obtain the aqueous-phase intrinsic reaction-rate constant. Comparing the results obtained from experiments, the aqueous-phase reaction rate is essentially instantaneous relative to the organic-phase reaction rate. The resistance of mass transfer of catalyst between two phases is negligible. The reaction rate in the organic phase is a rate-determining step for the two-phase reaction. The results obtained from the model’s prediction are closely consistent with the experimental data obtained from the phase-transfer catalytic reactions.