Reaction and complex formation between OH radical and acetone

Kinetics and mechanism of the reaction of OH with CH3C(O)CH3 have been stud ied by discharge-flow experiments and CCSD(T) quantum chemical computations . In the experiments, the rate coefficient for the overall reaction, OH + C H3C(O)CH3 --> products (1), and the branching ratio for the specific reacti on channel OH + CH3C(O)CH3 --> CH2C(O)CH3 + H2O (1a) have been determined t o be k(1) = (1.04 +/- 0.03) x 10(11) cm(3) mol(-1) s(-1) and Gamma (1a) = k (1a)/k(1) = 0.50 +/- 0.04, respectively (T = 298 K). Two different reaction pathways have been characterized by ab initio calculations. Both H atom ab straction and OH addition to the C=O group have been found to occur through hydrogen bonded OH . . . CH3C(O)CH3 complexes. Most of our results support recent findings (M. Wollenhaupt, S. A. Carl, A. Horowitz and J. N. Crowley , J. Phys. Chem. A, 2000, 104, 2695; M. Wollenhaupt and J. N. Crowley, J. P hys. Chem. A, 2000, 104, 6429) but contradictions remain concerning the mec hanism of this atmospherically important reaction.