The reaction of OH with acetone and acetone-d6 from 298 to 832 K: Rate coefficients and mechanism

The pulsed laser photolysis/pulsed laser-induced fluorescence technique has been applied to obtain rate coefficients for OH+CH3C(O)CH3 and CD3C(O)CD3 of kH(298–832 K)=(3.99±0.40)×10−24T4.00 exp(453±44)/T and kD(298–710 K)=(1.94±0.31)×10−21T3.17 exp(−529±68)/T cm3 molecule−1 s−1, respectively. Three pathways were characterized via the CBS–QB3 ab initio method to obtain complete basis set limits for coupled-cluster theory. Addition to form CH3C(O)(OH)CH3, followed by dissociation to CH3+CH3C(O)OH, is negligibly slow. Variational transition state theory reveals that the dominant products are CH3C(O)CH2+H2O formed by direct abstraction at higher temperatures and via a hydrogen-bonded complex below about 450 K. Inclusion of tunneling gives good accord with the observed kinetic isotope effect down to about 250 K.