Abstract: A catalyst complex useful for converting normal C.sub.4 hydrocarbons to maleic anhydride in vapor phase comprising as components vanadium, phosphorus, copper, an element selected from the group of Te, Zr, Ni, Ce, W, Pd, Ag, Mn, Cr, Zn, Mo, Re, Sm, La, Hf, Ta, Th, Co, U, and Sn, preferably with an alkali or alkaline earth metal.

Abstract: In autoxidation of tertiary cycloalkanes and alkyl aromatics the selectivity for organic hydroperoxides can be substantially increased by using a basic or amphoteric buffering compound of a Group IIIB or rare earth metal. For example, an autoxidation of isopentane with 4 wt. percent LaO at 11.1 mole percent conversion gave selectivities of t-amyl hydroperoxides -- 75.5 mole percent, acetone -- 18.3 mole percent, and t-amyl alcohol -- 0.3 mole percent. The same reaction without the buffer at only 10.3 mole percent conversion ve selectivities of t-amyl hydroperoxide -- 30.6 mole percent, acetone -- 51.2 mole percent and t-amyl alcohol -- 14.9 percent.