11024
J. Am. Chem. Soc. 1999, 121, 11024-11025
Evidence for Two Competing Mechanisms for n-Butane Oxidation Catalyzed by Vanadium Phosphates Bin Chen and Eric J. Munson* Department of Chemistry, UniVersity of Minnesota 207 Pleasant St. SE, Minneapolis, Minnesota 55455 ReceiVed August 12, 1999 The conversion of n-butane to maleic anhydride by vanadium phosphorus oxide (VPO) catalysts is recognized as one of the most complex selective oxidation reactions used in industry today, as it involves the abstraction of eight hydrogen atoms and insertion of three oxygen atoms.1-3 The reaction is proposed to proceed by either an alkoxide or an olefinic intermediate route. Under standard operating conditions no intermediates have been observed in the reaction products, so the proposed mechanisms for this reaction are based upon studies of the kinetics of the reaction and the observation of anticipated intermediates using nonstandard conditions.3,4 In the olefinic route, the reaction is proposed to proceed as shown:
This route is based on the observation of butenes, butadiene, and furan at very low concentrations (
