Reaction of Hydroxyl Radical with Acetone. 1. Kinetics of the Reactions of OH, OD, and¹⁸OH with Acetone and Acetone-<i>d</i>₆

Abstract

The rate coefficient for the reaction of OH with acetone, k 1, was measured by producing OH via pulsed laser photolysis and detecting it via laser-induced fluorescence to be k 1 ( T ) = 1.38 × 10 -13 + 3.86 × 10 -11 exp(−1997/ T ) cm 3 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 k 1 suitable for atmospheric calculations is deduced from our data and that from previous work to be k 1 = 1.39 × 10 -13 + 3.72 × 10 -11 exp(−2044/ T ) cm 3 molecule -1 s -1 . The rate coefficients at 298 K for the reaction of OH with CD 3 C(O)CD 3 ( k 4 ), OD with CH 3 C(O)CH 3 ( k 2 ), and OD with CD 3 C(O)CD 3 ( k 5 ) were measured to be (in units of cm 3 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 18 OH with acetone does not produce 16 OH. The large primary kinetic isotope effect (i.e., the large value of k 1 / k 4 and k 2 / k 5 ) at 298 K and its increase with decreasing temperature suggests that OH abstracts an H atom from acetone. k 1 was found to be independent of bath gas pressure between 1 and 490 Torr and independent of bath gas (He, N 2, or SF 6 ). The products and mechanism of the OH−acetone reaction is discussed in the companion paper.