RECOIL TRITIUM REACTIONS: METHYL CHLORIDE

Recoil tritium reactions with CH/sub 3/Cl give three importart hot products HT, CH/sub 2/TCl, and CH/sub 3/T, in the approxiraate ratios 2.7: 1.0:0.8 at 1 atmosphere pressure. When I/sub 2/ is used as the radical scavenger, CH/sub 2/TI is observed in yields comparable to that of CH/sub 2/TCl. Variation of the gas pressure during irradiation shows that the yields of CH/sub 2/TCl and CH/sub 2/TI are pressure dependert in a manner consistent with the reaction CH/sub 2/TCl* yields CH/sub 2/T + Cl. Measurements in the liquid phase indicate that approximately half of the original molecules formed by substitution of T for H decompose at 1 atm. gas pressure before de-excitation can occur. The relative ease of replacement of H by T per C--H bond is about 0.78 to 1 for CH/sub 3/Cl vs cyclo-C/sub 4/H/sub 8/. The pressure-dependent reactions demonstrate the presence of a long-lived excited molecule and indicate that most of the observed CH/sub 2/T radicals are formed through a two-step mechanism. Steric inhibition of hot substitution reactions by Cl substituents is a small effect at most. (auth)