Theoretical enthalpies of formation of ROX (R=H, CH3; X=F, Cl, Br) compounds

Standard enthalpies of formation of ROX (R=H, CH3; X=F, Cl, Br) compounds were theoretically estimated using hydrogenation reactions as working chemical reactions. Energy differences were computed at four ab initio levels of calculation, using gaussian-2 (G2) theory (Level I), coupled-cluster theory with split-valence basis set (Level II), coupled-cluster theory with triple-zeta basis set (Level III), and Truhlarʹs basis-set limit method (Level IV). The recommended standard enthalpies of formation (at 298.15 K and 1.0 atm) are the unweighted averages of the results obtained at Levels I and IV from the different hydrogenation reactions, namely: FOH, −21.1±0.3; ClOH, −18.5±0.5; BrOH, −15.2±1.1; CH3OF, −19.1±2.1; CH3OCl, −13.2±2.3, and CH3OBr, −8.7±2.7 kcal mol−1.