Microwave heating of heterogeneously catalysed Suzuki reactions in a micro reactor.

The Suzuki cross-coupling reaction of aryl halides with phenylboronic acid to form biaryls has been used to illustrate the development of a microwave based technique capable of delivering heat locally to a heterogeneous Pd-supported catalyst located within a micro reactor device. A 10-15 nm gold film patch, located on the outside surface of the base of a glass micro reactor, was found to efficiently assist in the heating of the catalyst when irradiated with 5-7 W of microwave power at 2.45 GHz. Using a hydrodynamically pumped system, reactant-catalyst contact times of less than 60 s were found to give conversions for different substrates which were in the range 50-99%. Two methods of loading catalysts into the micro reactor were investigated which required either 1.5 or 6 mg of material.