Application Note 61: Photochemical bromination with elemental bromine in continuous flow

In this application note, we demonstrate how to safely use solutions of bromine under a wide range of reaction conditions. This is achieved with the versatility of the Vapourtec E-series, V-3 pumps and our UV-150 photochemical reactor.

This application describes:

• Safe and easy pumping of an elemental bromine solution
• Effective and repeatable photobromination in a UV-150 photochemical reactor
• Rapid scale-up to over 10 g/hr

Safer Handling of Bromine

Elemental bromine is an efficient reagent for incorporating bromine into a range of benzyl, allylic and heterocyclic bromomethyl compounds but can present a hazard for handling in the laboratory. The resultant bromomethyl benzenes are often toxic and lachrymatory, and careful handling to avoid exposure is needed. Using the E-Series and UV-150 photochemical reactor it has been possible to carry out a range of photochemical brominations without needing to handle bromine, beyond making a stock solution.

Improved reaction rates

In the chemical literature, we found an example that required a significantly longer reaction time than any other example in the paper. Using the E-Series and UV-150 photochemical reactor, we have been able to reduce the reaction time from 7.5 minutes to 1 minute, with improved reaction yields (from 69% to 89%).