Ethyl radical isomerization. A 1,2-hydrogen (deuterium) shift in the pyrolysis of 1,1,1-trideuterioethane

1,1,1-Trideuterioethane has been pyrolyzed in the temperature range 500-600/sup 0/C. The reaction products are formed via chains initiated by C--C bond cleavage of ethane, but the hydrogen and deuterium content of the ethylene products and the H/sub 2/, HD, and D/sub 2/ yields are not predicted by the conventional mechanism. The results may be understood in terms of a mechanism involving isomerization of ethyl radical by a 1,2-H (or -D) shift along the carbon skeleton competing with abstraction from the parent and decomposition. The kinetic evidence suggests that the E/sub a/ for decomposition of ethyl radical and the 1,2 isomerization are within 1.5 kcal/mol, the difference in rate constants reflecting the difference in preexponential factors.