Gas phase reactions of C1-C4 alcohols with the OH radical:: A quantum mechanical approach

CCSD(T)//BHandHLYP/6-311G(d,p) calculations have been performed to study the OH hydrogen abstraction reaction from C-1-C-4 aliphatic alcohols. A complex mechanism involving the formation of a stable pre-reactive complex is proposed and the temperature dependence of the rate coefficients is studied over the temperature range of 290-500 K, using conventional transition state theory (CTST). Excellent agreement between calculated and experimental k at 298 K has been obtained. Arrhenius expressions are proposed for 1-propanol and 1-butanol, k(1-Prop) = 3.06 x 10(12)exp(140/T) and k(1-But) = 2.14 x 10(12)exp(440/T) cm(3) molecule(-1).s(-1), respectively. The rate coefficient for the formation of the alpha radical is found significantly larger than that of the competing channels for C-1-C-3 alcohols. The finding that at room temperature the rate constant of 1-butanol(gamma) is the largest one supports some of the previous experimental results.