Carbon nitride materials have emerged as an efficient and sustainable class of heterogeneous photocatalysts, particularly when paired with nickel in dual catalytic cross-coupling reactions.

Performing these transformations on larger scales using a continuous process is difficult due to the problems associated with handling solids in flow. By combining an oscillatory pump with a microstructured plug flow photoreactor, a stable suspension of the photocatalyst can be maintained, circumventing clogging of the reactor channels. Through careful tuning of the oscillator properties, the residence time distribution (RTD) was optimized, whilst maintaining a stable catalyst suspension. Short residence times (20 min) were achieved using optimized conditions and the recyclability of the photocatalyst was demonstrated over 10 cycles with no loss of activity. During a stable 4.5 hour scale-out demonstration, the model substrate could be isolated on 12 g scale (90% yield, 2.67 g h−1). Moreover, the method was applied for the gram scale synthesis of an intermediate of the active pharmaceutical ingredient tetracaine.

Rosso, C.; Gisbertz, S.; Williams, J. D.; Gemoets, H. P. L.; Debrouwer, W.; Pieber, B.; Kappe, C. O. React. Chem. Eng. 2020, 5., 2021, 23 (3), 597–604.

https://doi.org/10.1039/D1GC02039K