Going with the flow

20th November 2020

Recent compounds synthesised under continuous flow conditions at Apollo Labs

Picture 1. Vapourtec R-series flow reactor, fitted with a photochemical reactor at Apollo Labs.

Benzylic bromides are important building blocks in the pharmaceutical and agrochemical industries to synthesise benzylamides, benzylamines, benzyl sulfonmaides and N-benzyl heterocyclic compounds. To increase our range of available benzyl bromides we have been working on benzylic brominations, under continuous photochemical flow conditions, putting our Vapourtec R-series flow reactor through its paces. Stock solutions of the toluene derivatives and a Br-source were mixed and pumped through the photochemical reactor to obtain the benzyl bromides. We also managed to selectively synthesis benzal bromides to access otherwise difficult to synthesise benzaldehyde derivatives. A few examples of our recent work are shown below and all are available from stock on our website.

Most recently we have scaled-up the synthesis of one compound, to process just over 300g of the toluene starting material a day. We successfully made a total of 5.5 kg of the desired benzyl bromide, within 4 weeks; running the flow reactor 18 h/day.

The following items have been synthesised under continuous flow conditions:

     OR18742   3-BROMO-2-METHOXYBENZYL BROMIDE

  OR400770   4-BROMO-2-FORMYLBENZOIC ACID

      OR400774   2-BROMO-6-FORMYLBENZOIC ACID

            OR950728   3-BROMO-6-METHYL-5,6-DIHYDRO-7H-PYRROLO[3,4-B]PYRIDIN-7-ONE

      PC1067   2-BROMO-5-(TRIFLUOROMETHOXY)BENZYL BROMIDE

      PC501140   METHYL 3-(BROMOMETHYL)-5-FLUOROPHENYLACETATE