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Reaction of Hydroxyl Radical with Acetone. 1. Kinetics of the Reactions of OH, OD, and 18 OH with Acetone and Acetone- d 6

2003; American Chemical Society; Volume: 107; Issue: 25 Linguagem: Inglês

10.1021/jp027301a

1520-5215

Tomasz Gierczak, Mary K. Gilles, Stefan Bauerle, A. R. Ravishankara,

Spectroscopy and Laser Applications

The rate coefficient for the reaction of OH with acetone, k1, was measured by producing OH via pulsed laser photolysis and detecting it via laser-induced fluorescence to be k1(T) = 1.38 × 10-13 + 3.86 × 10-11 exp(−1997/T) cm3 molecule-1 s-1. These results confirm the rate coefficient data of Wollenhaupt et al. (J. Phys. Chem. A 2000, 104, 2695). A value of k1 suitable for atmospheric calculations is deduced from our data and that from previous work to be k1 = 1.39 × 10-13 + 3.72 × 10-11 exp(−2044/T) cm3 molecule-1 s-1. The rate coefficients at 298 K for the reaction of OH with CD3C(O)CD3 (k4), OD with CH3C(O)CH3 (k2), and OD with CD3C(O)CD3 (k5) were measured to be (in units of cm3 molecule-1 s-1) (3.00 ± 0.04) × 10-14, (2.07 ± 0.14) × 10-13, and (3.26 ± 0.16) × 10-14, respectively; they were also measured at a few temperatures above and below 298 K. It was deduced that the reaction of 18OH with acetone does not produce 16OH. The large primary kinetic isotope effect (i.e., the large value of k1/k4 and k2/k5) at 298 K and its increase with decreasing temperature suggests that OH abstracts an H atom from acetone. k1 was found to be independent of bath gas pressure between 1 and 490 Torr and independent of bath gas (He, N2, or SF6). The products and mechanism of the OH−acetone reaction is discussed in the companion paper.