The Reactions Between Atomic Deuterium and the Saturated Aliphatic Hydrocarbons

Abstract

The exchange reactions between atomic deuterium and methane, ethane, propane and butane have been studied in the range of temperatures, 0–300°C, in each case until significant amounts of exchange have been obtained. The extent of deuterization and the nature of the fragments produced have been examined by fractionation analysis and determination of the thermal conductivities of the fractions. From the temperatures at which the several interactions occur, approximate values for the activation energies of the individual processes have been deduced and these have been shown to conform with the mechanisms of reaction formulated. It has been indicated that deuterization of alkyl radicals in presence of atomic deuterium is a more rapid process than the deuterization of the saturated hydrocarbons. From the activation energies obtained, values for the bondenergies CH3–H=108 kcal. and CH3–CH3=97.6 kcal. have been deduced. The discrepancies between these and other values have been emphasized. The uncertainty of the value of the steric factor in the activation energy calculations has been indicated and its influence on the results derived has been exhibited.