화학공학소재연구정보센터
Journal of Physical Chemistry, Vol.99, No.18, 6913-6916, 1995
Direct Evidence for Preferential Beta-C-H Bond-Cleavage Resulting from 248 nm Photolysis of the N-Propyl Radical Using Selectively-Deuterated 1-Bromopropane Precursors
A series of selectively-deuterated 1-bromopropane precursors have been used to study site-specific photolysis in the n-propyl radical. A two-color photolysis approach (222 nm followed by 248 nm radiation) is used to create an intermediate photofragment and produce an H or a D atom, which is detected by 1 + 1 resonance ionization through Lyman-alpha. Target precursors are BrCH2CD2CD3, BrCD2CH2CD3, and BrCD2CD2CH3 as well as BrCD2CH2CH3, BrCH2CD2CH3, and BrCH2CH2CD3. The "enhanced" H (or D) atom signals clearly demonstrate that C-H (or C-D) bond cleavage at the beta position is strongly favored. The net enhancement process undoubtedly involves photolysis of an intermediate, almost certainly the n-propyl radical. A comparison with systems involving ethyl and isopropyl radical photolysis is also presented.