Comparing Gas–Liquid Segmented and Tube-in-Tube Setups for the Aerobic Dimerization of Desmethoxycarpacine with an Automated Flow Platform

Abstract

The hazardous nature of molecular oxygen can be mitigated with the use of flow reactors of small size, which in turn accelerate the gas-to-liquid mass transfer rate. In this contribution, we describe a reconfigurable automated flow platform integrating on-line HPLC monitoring for the cobalt-catalyzed aerobic oxidative dimerization of desmethoxycarpacine to carpanone. The flow platform was configured for aerobic oxidation under either a gas–liquid segmented or tube-in-tube strategy. An extensive optimization study concluded that the tube-in-tube device was penalized by the use of expensive and fragile Teflon AF-2400 tubing while the gas–liquid segmented setup featured higher yields (62% vs 48%), shorter reaction times (5 min vs 20 min), and better robustness.