Continuous flow synthesis of the iodination agent 1,3-diiodo-5,5-dimethyl-imidazolidine-2,4-dione telescoped with semi-continuous product isolation

A batch synthesis to the iodinating agent 1,3-diiodo-5,5-dimethyl-imidazolidine-2,4-dione (DIH) was devised and developed. This batch process was then up-scaled (10×) and optimized by means of statistical experimental design and multivariate regression. The optimized batch procedure was then transferred and adapted for continuous flow synthesis using a multi-jet oscillating disk (MJOD) continuous flow reactor platform to provide a flow process that allowed a throughput of 47 g h−1 with a residence time of 9 min. A semi-continuous work-up step based on vacuum filtration was established and successfully telescoped to be an integrated part of the flow process. An 8 h test run using the optimized flow synthesis in combination with the semi-continuous filtration step afforded 375 g (≈90% isolated yield) of the pure title compound that was collected from 14 filtration batches of 25–27 g each