ISOTOPE EFFECT IN-DIFFUSION OF METHYL RADICALS IN GLASSY ETHANOL-1,2D(5) AT LOW-TEMPERATURES

The kinetics of methyl radicals decay has been studied at 77 K and at 90 K in glassy mixtures 0.9(xC(2)H(5)OH + (1 - x)C2D5OH) + 0.1H(2)O. I t has been shown that in matrices with a small content of H-component (x less than or similar to 0.02) the decay rate of CD3 radicals is not iceably higher than that of CH3. Upon H/D substitution in the methyl r adical the rate of radical migration and the rate of deuterium atom ab straction from matrix molecules change simultaneously. As the fraction of C2H5OH in the mixture increases, the difference in the rates of th e decay of methyl radical isotopomers vanishes. The unusual ''inverse' ' isotope effect in the methyl radical diffusion is considered in the framework of the transition state theory. (C) 1998 Elsevier Science B. V. All rights reserved.