Enhanced Telescoped Continuous-Flow Synthesis of Vanillin via Process Intensification Using Robust Cobalt Catalysts and Online UHPLC Analysis

We report a telescoped continuous-flow process for vanillin synthesis utilizing a newly developed CoOx/HT catalyst. This robust and highly selective catalyst achieves the continuous synthesis of vanillin with 90% yield and excellent selectivity through aerobic oxidative decarboxylation from vanillylmandelic acid. The use of a catalyst that shows high performance even under high-concentration conditions enables improvements in productivity and significant reductions in solvent consumption throughout the entire flow process. Therefore, a continuous-flow process consisting of two reaction steps, including a catalytic reaction and three in-line extraction steps, demonstrates continuous vanillin synthesis with a total yield, productivity, and STY of 67%, 12 g h–1, and 30 g h–1 L–1, respectively.