文摘
An expeditious and multikilogram-scale process for the Balz鈥揝chiemann synthesis of o-difluorobenzene from o-fluoroaniline via two separate continuous flow reactors in 90.0% yield has been set up. The main steps involved the generation of stable diazonium fluoborate intermediate in situ via continuous diazotization reactor at 20 掳C, and the choice of o-difluorobenzene as cosolvent to achieve the continuous flow fluorodediazoniation system. Reaction time of both steps could be brought down to within 10 s and 2 min, respectively, by increasing the reaction temperature and thereby taking advantage of improved mass and heat transfer of a continuous flow system.