Rate constant for the reaction of CH 3 C(O)CH 2 radical with HBr and its thermochemical implication

The fast flow method with laser induced fluorescence detection of CH 3 C(O)CH 2 was employed to obtain the rate constant of k 1 (298 K) = (1.83 ± 0.12 (1σ)) × 10 10 cm 3 mol −1 s −1 for the reaction CH 3 C(O)CH 2  + HBr ↔ CH 3 C(O)CH 3  + Br (1, −1). The observed reduced reactivity compared with n ‐alkyl or alkoxyl radicals can be attributed to the partial resonance stabilization of the acetonyl radical. An application of k 1 in a third law estimation provides Δ f H   o 298 (CH 3 C(O)CH 2 ) values of −24 kJ mol −1 and −28 kJ mol −1 depending on the rate constants available for reaction (‐1) from the literature. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 38: 32–37, 2006