Kinetic study of the reactions of Cl atoms with CF2CH2CH2OH, CF3CF2CH2OH, CHF2CF2CH2OH, and CF3CHFCF2CH2OH

The reaction kinetics of chlorine atoms with a series of partially fluorinated straight-chain alcohols, CF3CH2CH2OH (1), CF3CF2CH2OH (2), CHF2CF2CH2OH (3), and CF3CHFCF2CH2OH (4), were studied in the gas phase over the temperature range of 273-363 K by using very low-pressure reactor mass spectrometry. The absolute rate coefficients were given by the expressions (in cm(3) molecule(-1) s(-1)): k(1) = (4.42 +/- 0.48) x 10-(11) exp(-255 +/- 20/T); k(1)(303) = (1.90 +/- 0.17) x 10-(11), k(2) = (2.23 +/- 0.31) x 10-(11) exp(-1065 +/- 106/ T); k(2)(303) = (6.78 +/- 0.63) x 10-(13), k(3) (8.51 +/- 0.62) x 10(-12) exp(-681 +/- 72/T-); k(3)(303) = (9.00 +/- 0.82) x 10-(13) and k(4) = (6.18 +/- 0.84) x 10(-12) exp(-736 +/- 42/7-); k(4)(303) = (5.36 +/- 0.51) x 10(-13). The quoted 2 sigma uncertainties include the systematic errors. All title reactions proceed via a hydrogen atom metathesis mechanism leading to HCl. Moreover, the oxidation of the primarily produced radicals was investigated, and the end products were the corresponding aldehydes (R-F;-CHO; R-F = -CH2CF3, -CF2CF3, -CF2CHF2, and -CF2CHFCF3) providing a strong experimental, indication that the primary reactions proceed mainly via the abstraction of a methylenic hydrogen adjacent to a hydroxyl group. Finally, the bond strengths and ionization potentials for the title compounds were determined by density functional theory calculations, which also suggest that the alpha-methylenic hydrogen is mainly under abstraction by CI atoms. The correlation of room-temperature rate coefficients with ionization potentials for a set of 27 molecules, comprising fluorinated C2-C5 ethers and C2-C4 alcohols, is good with an average deviation of a factor of 2, and is given by the expression log(k) (in cm(3) molecule(-1)s(-1)) = (5.8 +/- 1.4) - (1.56 +/- 0.13) x (ionization potential (in eV)).