Furan production by oxygen insertion in the 1–4 position of butadiene on V-P-O-based catalysts

Abstract

Furan formation from butadiene on a vanadium-phosphorus catalyst prepared in an organic medium is examined. The furan yield can be increased up to about 30%, operating at low conversion and at oxygen/butadiene ratios in the 1.5 – 2.0 range. This value cannot be increased further, due to the similarity of the mechanism of furan formation from butadiene and further furan oxidation to maleic anhydride and due to the self-inhibition of butadiene on the formation of furan. Comparison of the butadiene oxidation with that of furan and 2,5-dihydrofuran suggests that the mechanism of oxidation occurs through an electrophilic oxygen attack on the 1,4 butadiene positions to give 2,5-dihydrofuran, which is further converted by allylic dehydrogenation to furan. This intermediate, in turn, is further converted to maleic anhydride by the insertion of oxygen in the 2–5 furan positions and subsequent allylic dehydrogenation.