Radiolysis of Methylcyclohexane. I. Liquid Phase

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Abstract
The gamma‐radiolysis of liquid methylcyclohexane has been studied over the dose range 0.40 to 35.0×1019 ev/ml. The initial 100 ev yields of the products are: H2, 4.80±0.07; (1‐methylcyclohexene+methylenecyclohexane), 2.65±0.15; (3‐methylcyclohexene+4‐methylcyclohexene), 0.83±0.10; open chain heptene′, 0.33±0.02; open chain heptene″, 0.31±0.04; bi‐methylcyclohexyl, 0.75±0.05; methylcyclohexylheptene, 0.13±0.02. Methylcyclohexyl‐methylcyclohexene was a secondary product, resulting mainly from reaction of methylenecyclohexane and partly from reaction of 1‐methylcyclohexene. The values of the ratios of the olefin yields to the ``dimer'' yields in the cyclohexane and methylcyclohexane systems were compared with values of disproportionation to combination ratios for moderately bulky alkyl radicals in the gas phase. It was concluded that the major portions of the olefins and ``dimers'' in the radiolytic systems were formed by the disproportionation and combination of radicals. A steric hindrance effect probably has a small influence on the rate of the combination reaction. It was illustrated that a polymerization reaction occurs, involving the olefinic products, although the polymer could not be characterized. The relative significance of the polymerization reaction increases with decreasing dose rate.