PHOTOLYSIS OF LIQUID CYCLOHEXANE AND CYCLOHEXANE SOLUTIONS IN VACUUM ULTRAVIOLET

Liquid cyclohexane and cyclohexane solutions were photolyzed at 1236 and 1470 Å. The products and quantum yields for cyclohexane photolysis at 1470 Å are hydrogen (1.0), cyclohexene (0.94), dicyclohexyl (0.06), ethylene (0.003) and butadiene (0.001). Products and relative yields at 1236 Å are hydrogen (1.0), cyclohexene (0.93), dicyclohexyl (0.05), ethylene (0.06) and butadiene (0.02). The addition of benzene or cyclohexene as solutes caused drastic reductions in the rate of cyclohexane decomposition. A significant fraction of the decreases in the product yields is attributed to the scavenging of hydrogen atoms by the solute. The ratio of the rate constant for hydrogen atom addition to benzene to that of hydrogen abstraction from cyclohexane is about 300. Neutral excited cyclohexane molecules are found to be important intermediates, and the major effects of benzene and cyclohexene as solutes are accounted for by quenching of these excited species. The rate-constant ratio for energy transfer to the solute and dissociation of the excited intermediate is about 3.2 liter/mole.