Uda, T; Egashira, M; Seiyama, T
Reaction scheme of oxidative dehydroaromatization, i. e., oxidation of lower olefins to aromatics over bismuth phosphate or stannic oxide catalysts, was investigated by comparing the products from various C8-C8 hydrocarbons. n-Butenes were mainly oxidized to butadienes, which were known to be formed via the allylic intermediate, and partially to aromatics and diolefins. The same distribution of products was obtained for three isomers of n-butenes. Isobutene was converted to 2,5-dimethyl-1, 5-hexadiene and consecutively to p-xylene. From 1,5-hexadiene, 1,3,5-hexatriene was formed together with benzene. Both cyclohexane and cyclohexene were converted to benzene and 1,3,5-hexatriene by parallel reactions, and their aromatization rates were relatively slow, while 1,3-cyclohexadiene was readily dehydrogenated to benzene. These results suggest that the reaction proceeds through several consecutive steps: (1) the oxidative dehydrogenation of olefins to allylic intermediates, (2) the dimerization of allylic intermediates to 1,5-hexadienes, (3) the oxidative dehydrogenation of 1,5-hexadienes to hexatrienes, (4) the cyclization of hexatrienes to 1,3-cyclohexadienes, and (5) the aromatization of 1,3-cyclohexadienes. 1972, The Chemical Society of Japan. All rights reserved.