Direct kinetic study of reactions of hydroxyl radicals with alkyl formates

Rate coefficients were determined for the gas phase reactions of hydroxyl radicals with a series of alkyl formats. Experiments were carried out using the isothermal fast flow method coupled with resonance fluorescence detection. The obtained room temperature rate coefficients are (in 10(-13) cm(3) molecule(-1) s(-1) units): 1.83 +/- 0.33 (methyl formate), 9.65 +/- 0.43 (ethyl formate), 18.73 +/- 0.83 (isopropyl formate), 6.77 +/- 0.38 (tertbutyl formate) and 1.62 +/- 0.13 (methyl chloroformate). These results are compared with the literature data. In addition estimations are made for the partial reactivities of the formate group and for the hydrocarbon groups adjacent to HC(O)O. Moreover, it has been found that the partial reactivity of the HC(0)0 group (in reactions of OH with formates) is two orders of magnitude smaller than that of the HC(O) group (in reactions of OH with aldehydes). This has been explained using the results of ab initio calculations at the G3MP2//MP2(full)/6-31 G(d) level of theory.