Evaluation of a Continuous-Flow Photo-Bromination Using N-Bromosuccinimide for Use in Chemical Manufacture

A continuous-flow photo-bromination reaction on benzyl and phenyl groups was conducted using N-bromosuccinimide as the bromine source inside a preparatory-scale glass plate reactor. This flow reactor system was capable of independently controlling light intensity, wavelength, and reaction temperature, hence exerting an exceptional level of control over the reaction. A short optimisation study for the synthesis of 2-bromomethyl-4-trifluoromethoxyphenylboronic acid pinacol ester resulted in best conditions of 20 degrees Cand 10 min residence time using anLED (light-emitting diode) array at 405 nm and acetonitrile as the solvent. The present study evaluates the potential for this easy-to-handle bromination system to be scaled up for chemical manufacture inside a continuous-flow glass plate reactor. The combination with an in-line continuous flow liquid-liquid extraction and separation system, using a membrane separator, demonstrates the potential for continuous flow reaction with purification in an integrated multi-stage operation with minimal manual handling in between.

Automated summary

By utilizing a flow reactor system, it is possible to independently control light intensity, wavelength, and reaction temperature, thereby enhancing control over the reaction. The study demonstrated that under specific conditions, the target product can be efficiently synthesized, and this easy-to-handle reaction system has the potential for scaled-up production.