Reaction of C2(a 3Πu) with methanol: temperature dependence and deuterium isotope effect.
Bimolecular rate constants for the gas-phase reactions of C(2)(a (3)Π(u)) with a variety of methanol isotopomers including CH(3)OH (k(1)), CH(3)OD (k(2)), CD(3)OH (k(3)), and CD(3)OD (k(4)) have been measured over the temperature range of 293-673 K by means of pulsed laser photolysis/laser-induced fluorescence technique. The rate constants, in units of cm(3) molecule(-1) s(-1), can be fitted by the normal Arrhenius expressions: k(1)(T)=(1.32±0.02)×10(-11)×exp[-(366.80±4.44)/T], k(2)(T)=(1.34±0.02)×10(-11) exp[-(376.86±5.09)/T], k(3)(T)=(1.09±0.02)×10(-11) exp[-(640.00±7.23)/T], and k(4)(T)=(1.12±0.01)×10(-11)×exp[-(666.37±4.63)/T], where all error estimates are ±2σ and represent the precision of the fit. The observed deuterium kinetic isotope effects, k(1)/k(2) and k(1)/k(3), along with the positive temperature dependences of k(T), allow us to reach a conclusion that the reaction of C(2)(a (3)Π(u)) with methanol in 293-673 K proceeds via a site-specific hydrogen abstraction mechanism, that is, H-atom abstraction from the methyl site rather than from the hydroxyl site dominating reactivity.
Hu
Renzhi
R
Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
Zhang
Qun
Q
Chen
Yang
Y