The overall rate constants for the reactions of
hydroxyl radicals (
OH) with four small methyl
esters, namely
methyl formate (CH(3)OCHO),
methyl acetate (CH(3)OC(O)CH(3)), methyl
propanoate (CH(3)OC(O)C(2)H(5)), and
methyl butanoate (CH(3)OC(O)C(3)
H(7)), were investigated behind reflected
shock waves using UV
laser absorption of
OH radicals near 306.69 nm. Test gas mixtures of individual methyl
esters and
tert-butyl hydroperoxide (TBHP), a fast source of
OH at elevated temperatures, diluted in
argon were
shock-heated to temperatures spanning from 876 to 1371 K at pressures near 1.5 atm. The overall rate constants were determined by matching the measured
OH time-histories with the computed profiles from the comprehensive chemical kinetic mechanisms of Dooley et al. (2010) and Dooley et al. (2008), which were originally developed for the oxidation of
methyl formate and
methyl butanoate, respectively. These measured values can be expressed in Arrhenius form as k(CH(3)OCHO+OH) = 2.56 × 10(13) exp(-2026/T) cm(3) mol(-1) s(-1), k(CH(3)OC(O)CH(3)+
OH) = 3.59 × 10(13) exp(-2438/T) cm(3) mol(-1) s(-1), k(CH(3)OC(O)C(2)H(5)+
OH) = 6.65 × 10(13) exp(-2539/T) cm(3) mol(-1) s(-1), and k(CH(3)OC(O)C(3)
H(7)+
OH) = 1.13 × 10(14) exp(-2515/T) cm(3) mol(-1) s(-1) over the temperature ranges studied. Detailed error analyses were performed to estimate the overall uncertainties of these reactions, and the estimated (2σ) uncertainties were found to be ±29% at 913 K and ±18% at 1289 K for k(CH(3)OCHO+OH), ± 29% at 930 K and ±17% at 1299 K for k(CH(3)OC(O)CH(3)+
OH), ± 25% at 909 K and ±17% at 1341 K for k(CH(3)OC(O)C2H(5)+
OH), and ±24% at 925 K and ±16% at 1320 K for k(CH(3)OC(O)C(3)
H(7)+
OH). We believe these are the first direct high-temperature rate constant measurements for the reactions of
OH with these small methyl
esters. These measured rate constants were also compared with the estimated values employed in different comprehensive kinetic mechanisms. Additionally, the structure-activity relationship from Kwok and Atkinson (1995) was used to estimate these four rate constants, and the estimations from this group-additivity model are in good agreement with the measurements (within ~25%) at the present experimental conditions.