Telescoped Two-Step Continuous-Flow Synthesis of Vanillin

This paper presents a novel telescoped continuous-flow process for vanillin synthesis that involves the use of two flow reactors, three in-line liquid–liquid extraction (LLE) systems, and an in-line gas–liquid separator. The highly efficient flow reaction process achieves a space-time yield that is at least 24 times higher than that of the conventional process. The optimized in-line LLE system enables the recycling of raw materials and solvents while reducing solvent usage, which results in a 50% reduction of process mass intensity. Employing this highly efficient, green process results in the continuous synthesis of vanillin, with a yield of 71% and a throughput of 2.3 g·h–1.