Theoretical structural and thermochemical characterization of partially fluorinated alcohols

Abstract

Molecular conformations, harmonic vibrational frequencies and standard enthalpies of formation for CH3-nFnCF2CH2OH, CH3-nFnCH2OH and CH3-nFnOH (n = 1,2,3) partially fluorinated alcohols were computed at different levels of theory using isodesmic and isogiric work reactions. The lack of data and large uncertainties in the reported thermodynamic properties motivated the present study. As average at the G4 and CBSQB3 levels of theory, standard enthalpies of formation at 298 K of −313.9±1.8, −258.2±1.8 and −208.4±1.8 kcal mol−1 were computed for CF3CF2CH2OH, CHF2CF2CH2OH and CH2FCF2CH2OH, respectively; values of −213.0±1.7, −154.5±1.7 and −100.4±1.7 kcal mol−1 were obtained for CF3CH2OH, CHF2CH2OH and CH2FCH2OH; while −216.9±1.2, −159.8±1.2 and −100.9±1.7 kcal mol−1 were derived for CF3OH, CHF2OH and CH2FOH. The corresponding enthalpies of formation presented here for CF3CF2CH2OH and CH2FCF2CH2OH were predicted for the first time. Hydrogen abstraction reactions enthalpies by OH radicals were also estimated and comparisons with previously reported results were performed.