Thiol−Ene Coupling in a Continuous Photo‐Flow Regime. Issue 10 (4th September 2018)

• Record Type: Journal Article
• Authors: Janssens, Pieter; Debrouwer, Wouter; Van Aken, Koen; Huvaere, Kevin
• Is Part Of: ChemPhotoChem. Volume 2:Issue 10(2018)
• Page Start: 884
• Page End: 889
• Publication Date: 2018-09-04
• Subjects: click chemistry -- flow chemistry -- photochemistry -- photoinitiation -- thiol−ene coupling; Photochemistry -- Periodicals; Periodicals; Electronic journals; 541.35
• DOI: 10.1002/cptc.201800155
• Languages: English
• ISSNs: 2367-0932

Abstract

Abstract: Photoinitiated thiol−ene chemistry is a promising technique for use in chemical synthesis and related sciences. In view of scaling, the process was successfully transferred to a continuous flow regime with compelling results in terms of selectivity, efficiency, and productivity. A series of selected thiols and enes were reacted using 2, 2‐dimethoxy‐2‐phenylacetophenone as radical initiator to respond to the 365 nm UV‐LED source. Process parameters were evaluated and chemical cross‐reactivity of the different substrates was assessed. Optimization of conditions gave high productivity of the thio‐ether resulting from the model reaction between benzyl thiol and 1‐decene when performed under neat conditions. The robustness of this method was demonstrated by running it under continuous operation for an extended period of time, with product output reaching constant yields of 90–92 % as soon as the steady‐state regime was installed. The corresponding space–time yield was 9.75 kg l −1 h −1, an impressive value that further demonstrates scale‐up potential. Abstract : It all clicks into place : The thiol−ene click reaction under a continuous photo‐flow regime gives impressive output, despite small reactor volume and a low‐powered UV‐LED irradiation source. Productivity is boosted by efficient initiation, a favourable reactant ratio, neat conditions, and the use of scalable purification techniques.