FUNCTIONALIZATION OF PARAFFINIC HYDROCARBONS BY HETEROGENEOUS VAPOUR-PHASE OXIDATION. III. CONVERSION OF THE C-1-C-7 ALKANE SERIES

The activity and the selectivity of the vanadyl pyrophosphate catal. yst in the heterogeneous oxidation of C-1-C-7 alkane series is compared. The comparison of the reactivities of the linear, branched and cyclic alkanes suggests that (i) in the mechanism of activation the driving force is the formation of the corresponding olefins and (ii) rate determining step is the contemporaneous removal of two H atoms by a concerted mechanism. In the C2-C3 alkane oxidation only corresponding olefins are formed. n-Butane selectively give maleic anhydride, whereas n-pentane selectively forms maleic and phthalic anhydrides, together with smaller amounts of benzoic acid. In the oxidation of the other alkanes, on the contrary, principal product is the maleic anhydride, but the selectivity decrease on increase of the carbon atom number in the hydrocarbon.