Efficient oxidation of furoin and 5,5′-dihydroxymethyl furoin to α-diketone furanil over molybdenum and tungsten compounds with air

Efficient molybdenum- and tungsten-based catalysts have been reported for the oxidation of furoin and 5,5′-dihydroxymethyl furoin (DHMF) to furil and 5,5′-bihydroxymethyl furil (BHMF), respectively. The catalytic oxidation reactions were performed using oxygen in air as the accelerator in acetic acid solvent. Under the optimized reaction conditions and by using tetra-hexadecyltrimethyl ammonium octamolybdate ([CTAB] 4 Mo 8 O 26 ) as a catalyst, excellent conversions to furil (~   100%) and BHMF (~   94%) were observed in a shorter reaction time compared to the other catalysts. This oxidation reaction has been performed by using acetic acid as a solvent under air for the first time, and the catalysts can be readily recycled with no noticeable loss in their catalytic activity over five consecutive catalytic cycles. In this manner, the catalytic system developed in this work is a greener and more environmentally benign process for the oxidation of furoin and DHMF.