Kinetic study on oxidative bromination of 2,6-dichlorotoluene to 2,6-dichlorobenzyl bromide in a microchannel reactor under light irradiation

Abstract

Abstract 2,6-dichlorobenzyl bromide (DCBB) is an important drug intermediate for the preparation of antibacterial and antitumor agents. DCBB was prepared by the photocatalytic benzylic bromination of 2,6-dichlorotoluene (DCT) with hydrogen peroxide and hydrobromic acid as bromine source in a microchannel reactor, which belongs to a green and safe, economical and environmentally friendly process. Herein, the work focused on the investigation of kinetics of oxidative bromination of DCT to DCBB, and a kinetic model for this process was proposed. A series of kinetic data were obtained under kinetically controlled conditions by eliminating the mass transfer effects of liquid-liquid phases, and the experimental data were fitted nonlinearly using Matlab software. The results showed that the calculated values based on the kinetic model were in good agreement with the empirical values, and the preexponential factor and activation energy were 635.3 and 24.0 KJ/mol, respectively, and high concentration of DCT inhibit the response.