A. SOKOLOWSKA AND LARRYKEVAN
2220
Radiolysis of Liquid Hexafluoroethane
by A. Sokolowska and Larry Kevan Department of Chemistry, University of Kansas, Laurence, Kansas 660&
(Received December 30,1966)
The y radiolysis of liquid C2F6 a t -78" was studied. The 100-ev product yields (G) are CF4 (1.72), C3F8 (0.87), and n-C4FlO(0.45). With O2 added'as a radical scavenger, the yields are 0.97, 0.0, and 0.0, respectively. From these results G(CF3) = G(C2F5) = 2.5. The CFa/C2F5ratio differs from that found by epr by which only CF3 was observed.
A comparison of the radiation chemistry of perfluoroalkanes with alkanes is especially significant because of the large C-F bond strength. In alkane radiation chemistry in gas, liquid, and solid phases dimer is a major product. It is therefore clear that C-H bond breaks predominate over C-C bond breaks even though the C-H bond strength exceeds that of C-C by some 20 kcal. In gas phase perfluoroalkane radiolysis dimer is a minor product and the frequency of C-C bond break is equal to or greater than that of C-F bond break.'P2 The C-F bond strength is about 35 kcal greater than the C-C bond strength; this magnitude seems to be required to cause the shift in behavior described above. Here we report results on the liquid phase radiolysis of C2Fe which allow us to extend the comparison with alkanes from the gas to liquid phase. From the final reaction products certain radical yields are deduced. These are of particular interest since a recent epr study of liquid CzFe under steady-state radiolytic conditions showed that CF3 was the only radical present at high dose.
Experimental Section C2Fe was from Air Products, Inc., and contained
