Thermal Decomposition Processes in the System Tricyclo[3.3.0.02,6]octane-1,5-Cyclooctadiene

The thermal isomerization of tricyclo[3.3.0.02'6]octane in the gas phase at 1.5-mm. pressure in the temperature range from 327 to 366° is a homogeneous, first-order reaction. The rate of the reaction fitted the equation K = 3.22 X 1015 exp (-55,900 ± 1400/RT). The addition of propylene had no effect on the kinetics. The products that were observed (in the order of decreasing yield) were 4-vinylcyclohexene, 1,3-butadiene, and 1,5-cyclooctadiene. From separate studies of the pyrolysis of 1,5-cyclooctadiene and 4-vinylcyclohexene, it was concluded that tricyclooctane isomerized to 1,5-cyclooctadiene which in turn isomerized rapidly to 4-vinylcyclohexene. While 1,3-butadiene is a product of the pyrolysis of 1,5-cyclooctadiene, it is not certain that this is the only path by which it is formed from tricyclooctane. The kinetics of the pyrolysis of 1,5-cyclooctadiene was studied over the temperature range from 299.5 to 358.1° at 1.2-mm. pressure. From 299.5 to 327.3° the reaction seemed to be first order, homogeneous, and unaffected by the addition of propylene. Above this range the reaction was complex, although the products remained qualitatively the same. © 1964, American Chemical Society. All rights reserved.