A microreactor with phase-change microvalves for batch chemical synthesis at high temperatures and pressuresElectronic supplementary information (ESI) available. See DOI: 10.1039/c3lc50939g

We present a simple microreactor with dimethyl sulfoxide (DMSO) phase-change valves suitable for performing batch organic chemistry under high temperature and pressure conditions. As a proof of principle, we demonstrate a radiofluorination reaction important in the synthesis of [ 18 F]FAC, a new positron emission tomography biomarker for immune system monitoring and prediction of chemotherapy response. We achieved high radioactivity recovery (97 ± 1%, n = 3) and conversion efficiency (83 ± 1%, n = 3), comparable to that achieved with macroscale systems, but with a volume 30× smaller. This platform overcomes the limitations of previously reported phase-change valves in terms of compatibility with organic chemistry, and extends the range of reaction conditions for carrying out harsh batch chemistry at the microscale. DMSO phase-change valves extend the capabilities of batch microreactors to high temperatures and pressures.