Thermal dimerization of 1,3-butadiene: Kinetics of the formation of cis,cis-cycloocta-1,5-diene

The thermal reaction of 1,3-butadiene (BD) has been studied between 464 and 557°K at pressures between 49 and 450 torr. The products are 4-vinylcyclohexene (VCH) and cis, cis-cycloocta-1,5-diene (COD), and their formations are second order. The rate constant (in 1/mol · sec) for VCH is given by and that for COD by The thermal reaction of COD has also been studied. The temperature was varied from 505 to 586°K and the pressure from 15 to 51 torr. The rate constants (in sec^?1) for the formations of VCH and BD are given by A biradical mechanism seems to fit these results. The heat of formation and the entropy of COD are estimated.