A 0.5 M acetonitrile solution of methyl hydrocinnamate and NBS was then passed through the photo-CDR at 0.5 mL/min, residence time of 420 seconds, and the degree of conversion to the brominated product determined by NMR (Table ). For the fluidic system we used the IKA-Flow system and controlled the flow rate using either a restrictor or a 3D-printed back-pressure regulator . See supplementary information.