Reactions Involving Hydrogen and the Hydrocarbons

Abstract

The activation energies of the reactions H+CH₄=CH₃+H₂ (1) and D+CH₄=CH₃D+H (2) have been calculated by using the semi‐empirical method in combination with the treatment of directed valence used by Van Vleck and Voge. The activation energies for reactions (1) and (2) were found to be 9.5 kcal. and 37 kcal. This result agrees with the prediction of 40 kcal. of Rice and Teller for reaction (2). In addition it is found that the energy surface corresponding to the reaction H+CH₄ contains a basin 8 kcal. deep corresponding to a stable CH₃–H–H molecule. The rapid recombination of H atoms in the presence of methane, observed by Farkas and Melville is interpreted in terms of this CH₃–H–H intermediate. The experimental data on the reactions of hydrogen and deuterium atoms with hydrocarbons have been reinterpreted in terms of atom‐cracking reactions of the type D+C₂H₅→C₂H₅D→CH₃D+CH₃.