Study on Mechanism of the Reaction of Benzene in a Radiofrequency Plasma

Abstract

The reaction of benzene in a 13.56 MHz glow discharge plasma is described. Major products were the lower molecular weight hydrocarbons such as acetylene and methylacetylene due to the ring cleavage. Biphenyl and polymeric deposit on the reactor wall were the significant by-products. The effects of reaction conditions on the rate were examined, and the reaction scheme involving successive electron collisions was assumed. Thus, the difference in the reactivities of C₆H₆ and C₆D₆ could be explained consistently in terms of the life times of activated species, most likely electronically excited benzenes, formed by the first electron collision. Furthermore, theminor pathway giving rise to biphenyl was discussed, principally on the basis of the isotope effects observed in biphenyl formation in the reactions of C₆H₆ and C₆D₆ mixture, and phenyl cation was presented as one of the most responsible precursors.