The Reaction of Hydrogen Atoms With Isobutane

The reaction of hydrogen atoms with isobutane has been investigated by the Wood–Bonhoeffer discharge tube method, over a temperature range 30° to 250 °C. An activation energy of 10.5 ± 1.5 kcal. was obtained for the reaction.The nature of the products at a given temperature was found to depend upon the concentration of hydrogen atoms present. With low atom concentrations (5 to 9%) methane was essentially the only product at temperatures below 170 °C. At 250 °C., ethane was formed to the extent of approximately one-half the amount of methane. With higher atom concentrations (14 to 24%) ethane was formed in appreciable quantities at 140° to 170 °C., and exceeded the methane content at 250 °C. Small amounts of propane were formed at the higher temperatures.The results at low temperatures appear to be satisfactorily explained by assuming a primary dehydrogenation reaction:[Formula: see text]followed by a series of "atomic cracking" reactions. To account for the behaviour at higher temperatures, additional secondary reactions, involving decomposition of radicals and their reaction with molecular hydrogen, are assumed.