Photochemistry in batch fights a fundamental problem: light attenuates with depth, so only the outer shell of a flask does chemistry. Microreactors solve it structurally, the reaction runs in channels thin enough that every molecule sees the same photon flux. The result is faster, cleaner and more reproducible photochemistry.
Short optical path, usually hundreds of micrometers, means uniform irradiation and full use of the light. Small volumes mean high surface-to-volume ratios, so heat and mass transport are excellent and exotherms stay controlled. And continuous flow means the residence time in the light is the reaction time, a parameter you set with precision.
Yields rise and side products fall as the reaction runs at its optimal intensity everywhere, not just near the wall. Reactions that fail in batch due to long exposure, over-irradiation products, over-oxidations, often succeed in flow, because molecules leave the light when their residence time ends.
Choose channel material for transparency at your wavelength, glass and fluoropolymers dominate. Set residence time first, then tune concentration and intensity. Back-pressure regulation allows operation above the solvent boiling point if the chemistry demands. Sampling at steady state gives clean kinetics, wait at least three residence volumes before collecting.
High-value syntheses, photo-sensitive intermediates, oxygen-mediated chemistry with defined gas-liquid segments, and any process destined for scale-out: flow photoreactors scale by numbering-up parallel channels, preserving the photon environment that made the chemistry work.
Perfectlight's pilot-scale photochemistry platforms include flow configurations; see solutions.
