Synthesis of maleic and phthalic anhydrides from the mixture of cyclopentene and 1-pentene

The selective oxidations of cyclopentene, 1-pentene, and their mixture to maleic and phthalic anhydrides have been studied to gain information on the total utilization of olefins of C(5)-fraction. The highest selectivities for maleic anhydride, a single major organic product, in individual oxidations of cyclopentene and 1-pentene were obtained at complete or almost complete conversion, and then the main byproduct was phthalic anhydride. The cooxidation of the mixture of cyclopentene and 1-pentene at ca. 100% conversion, which was selected as optimized condition, gave no interaction between cyclopentene and 1-pentene. This result indicates that two reactants can be simultaneously utilized at one oxidation unit process. In contrast, the cooxidation at low degrees of conversion gave some interaction. It was only related to the slightly stronger adsorption of cyclopentene as compared to 1-pentene.