Transitioning from conventional batch to microfluidic processes for the efficient singlet oxygen photooxygenation of methionine

Singlet oxygen-based photocatalytic oxygenation reactions have emerged as an efficient technology to synthesize value-added organic molecules. Among organic substrates, bio-sourced molecules such as aminoacids or terpenes have a promising forecast as synthetic building blocks. A pseudo first-order kinetic study for the photocatalytic oxygenation of natural amino acid (L)-methionine was carried out in a macroscopic batch reactor. Various parameters were studied, including the effect of the photosensitizer (Rose Bengal, RB) concentration, the intensity of the light and the O2 flow in terms of apparent kinetic constants and space-time yields. The identification of important limiting parameters as pressure, gas flow or light efficiency during the photocatalytic oxygenation of methionine allowed its transition from macroscopic batch reactor to continuous-flow microreactor.