γ-Radiolysis of cyclohexane with electron scavengers. II. Solid cyclohexane at 77 °K

Abstract

The γ-radiolysis of homogeneous solid solutions of SF6 and N2O in cyclohexane has been examined at 77 °K. With SF6, yields of the major products, hydrogen, bicyclohexyl, and cyclohexene, were all reduced, and no large yields of other products were observed. Thus, since SF6 reduces hydrogen yields by capturing electrons, combination of the SF6 anion and cyclohexane cation does not lead to bond breaking. Experimental evidence suggests that the ratio of disproportionation to combination of cyclohexyl radicals in solid cyclohexane at ~ 186 °K is 0.3 ± 0.2.With N2O, hydrogen yields are decreased to 3.5 G units, but large yields of cyclohexene, bicyclohexyl, and cyclohexanol (4.7, 2.0, and 1.0 G units respectively) are produced. Thus combination of O− and the cyclohexane cation leads to a great deal of bond breaking. The yields are explained by a mechanism similar to Dyne's mechanism for the radiolysis of hydrocarbons. It was, however, necessary to assume that excited states of cyclohexane formed directly behave differently from those formed by electron–cation combination.