Formation of Toluene in Vapor-Phase Reaction of Cyclopentadiene with Acetylene over Silicon Carbide

The vapor-phase reaction of cyclopentadiene (CPD) with acetylene over silicon carbide has been investigated with reference to the formation of 2, 5-norbornadiene (2, 5-NBD) and toluene. The yield of 2, 5-NBD was enhanced with rise in the reaction temperature and showed a maximum yield at 420°C. On the other hand, the formation of toluene initiating at 400°C increased with increasing temperature and with a simultaneous decrease in the yield of (2, 5-NBD). At 550°C, the yield of toluene was 30% and the selectivity was 75%. The formation of toluene was also observed in the reaction of 2, 5-NBD. Therefore, it was concluded that 2, 5-NBD was an intermediate of toluene. This was consistent with the kinetic studies on the formation of toluene. The menchanism of the addition of acetylene to CPD was also discussed and as a result, the role of a radical mechanism, in addition to that of a concerted one, was also assumed.