132434-74-3Relevant academic research and scientific papers
Selectivity and enormous H/D isotope effects on H atom abstraction by CH3 radicals in solid methylsilane at 3.0 K-115 K
Komaguchi, Kenji,Ishiguri, Yuko,Tachikawa, Hiroto,Shiotani, Masaru
, p. 5276 - 5280 (2002)
An EPR study was carried out to elucidate the hydrogen atom abstraction from methylsilane (CH3SiH3) by a methyl radical, CH3SiH3 + .CH3 → CH3SiH2. + CH4, in a solid solution of CH3SiH3 containing 1 mol% CH3I at the low temperatures of 3 K-115 K. The EPR spectra observed after UV-photolysis of the CH3I at 77 K were attributed to a mixture of the CH3SiH2. radical and the .CH3 radical. In the CH3SiH3 system, the CH3SiH2. radical was the major product immediately after the photolysis, while the .CH3 radical was the major one in the CH3SiD3 system. The .CH3 radicals decayed following first order kinetics in the dark in both systems. The decay rate constants for the reaction were experimentally determined to be k(Si-H) = 3.6 × 10-2 s-1 and k(Si-D) = 6.9 × 106 s1 (k(Si-H)/k(Si-D) = 5.2 × 103) at 77 K; the associated apparent activation energies were Ea(Si-H) = 0.85 kJmol s1 and Ea(Si-D) = 8.9 kJmol s1 (Ea(Si-H/Ea(Si-D) = 1/10) above 20 K. A non-linear Arrhenius plot was obtained for the rate constant, k(Si-H), and the rate became almost independent of the temperature below 20 K. These results suggest that the quantum mechanical tunneling effect contributes significantly to the H atom abstraction from the -SiH3 group.
