High-temperature measurements of the reactions of oh with a series of ketones: Acetone, 2-butanone, 3-pentanone, and 2-pentanone

摘要

The overall rate constants for the reactions of hydroxyl radicals (OH) with a series of ketones, namely, acetone (CH _3COCH _3), 2-butanone (C _2H _5COCH _3), 3-pentanone (C _2H _5COC _2H _5), and 2-pentanone (C _3H _7COCH _3), were studied behind reflected shock waves over the temperature range of 870-1360 K at pressures of 1-2 atm. OH radicals were produced by rapid thermal decomposition of the OH precursor tert-butyl hydroperoxide (TBHP) and were monitored by the narrow line width ring dye laser absorption of the well-characterized R _1(5) line in the OH A-X (0, 0) band near 306.69 nm. The overall rate constants were inferred by comparing the measured OH time histories with the simulated profiles from the detailed mechanisms of Pichon et al. (2009) and Serinyel et al. (2010). These measured values can be expressed in Arrhenius form as k _9CH3COCH3+OH) = 3.30 ×10 _(exp)~(13)(-2437/T) cm ~3 mol ~(-1) s ~(-1), k C2H5COCH3+OH== 6.35 ×10 13exp(-2270/ T) cm 3 mol -1 s -1, k C2H5COC2H5+OH = 9.29 ×10 13exp(-2361/T) cm 3 mol -1 s -1, and k C3H7COCH3+OH = 7.06 ×10 13exp(- 2020/T) cm 3 mol -1 s -1. The measured rate constant for the acetone + OH reaction from the current study is consistent with three previous experimental studies from Bott and Cohen (1991), Vasudevan et al. (2005), and Srinivasan et al. (2007), within 20%. Here, we also present the first direct high-temperature rate constant measurements of 2-butanone + OH, 3-pentanone + OH, and 2-pentanone + OH reactions. The measured values for the 2-butanone + OH reaction are in close accord with the theoretical calculation from Zhou et al. (2011), and the measured values for the 3-pentanone + OH reaction are in excellent agreement with the estimates (by analogy with the H-atom abstraction rate constants from alkanes) from Serinyel et al. Finally, the structure-activity relationship from Kwok and Atkinson (1995) was used to estimate these four rate constants, and the estimated values from this group-additivity model show good agreement with the measurements (within ～25%) at the present experimental conditions.