A Gaussian-2 molecular orbital study of the unimolecular reactions of acetyl cyanide

Some possible unimolecular reactions of CH3C(O)CN in its ground electronic state have been studied with the G2 molecular orbital method. Among the reactions considered, only its decomposition to CO and CH3CN is exothermic (ΔH = −7.66 kcal mol−1) and its isomerization to CH3C(O)NC has an activation barrier (40.77 kcal mol−1) accessible at low temperature. CH3C(O)CN is predicted to be rather stable at room temperature in line with experiment since the former reaction channel and the second step of the latter channel by which CH3C(O)NC decomposes to CO and CH3NC both have very high barriers, viz. 109.47 and 100.31 kcal mol−1, respectively.