The Reactions of Deuterium Atoms with Methane and Ethane

The reactions of deuterium atoms with methane and ethane have been investigated, the atoms being produced by the discharge tube method and by photosensitization with mercury. The activation energies found were 11.7 Kcal. for methane, and 6.3 Kcal. for ethane. The mechanism of the latter reaction is discussed, and it is concluded that the measured activation energy is that of the reaction $$\mathrm{D}+{\mathrm{C}}_2{\mathrm{H}}_6={\mathrm{C}}_2{\mathrm{H}}_5+\mathrm{HD}.$$ Hence the reaction $$\mathrm{H}+{\mathrm{C}}_2{\mathrm{H}}_6={\mathrm{C}}_2{\mathrm{H}}_5+{\mathrm{H}}_2$$ must have approximately the same energy of activation. On this assumption the free radical chain theory of first order reactions is discussed in the light of the recent work of Patat and Sachsse.