(299d) Studies Toward Scalable Photochemical Reactions in Flow

Emily B. Corcoran, François Lévesque, Jonathan P. McMullen, and John R. Naber

Process Research and Development, Merck & Co., Inc., Rahway, New Jersey 07065, USA

In recent years, there has been a significant growth in the reports of reactions promoted by visible and UV light, often detailing highly selective transformations not feasible through non-photochemical, manifolds. Due to the unique advantages of these reactions, we foresee an increasing use of light-promoted transformations in the synthesis and production of API. The implementation of bimolecular, non-chain photochemical reactions on large scale remains a key challenge. The implementation of these transformations on large scale is most amenable to flow, due to most photochemical reactions requiring a high surface area to volume ratio for good efficiency. This presentation will highlight key parameters that need to be taken into account for an effective transition from lab scale to preparative scale, namely reactor geometry, selection of irradiation source, pathlength, and residence time. As part of the discussion, ongoing efforts by the flow chemistry team at Merck & Co., Inc. toward developing scalable photochemical reaction in flow will be presented in the form of several short case studies about our experiences with scaling photocycloadditions and multi-catalytic photochemical transformations.