Methane, appearance potentials atomization

Appearance potentials for CHg from CH and CHgF reported by Losslng, Ingold, and Henderson ( ), the enthalpies of dissociation of hydrogen (104.20 kcal) and fluorine (37.72 kcal), and the enthalpy of formation of methane (-17.90 kcal) were used to calculate the enthalpy of formation of gaseous CHgF. These authors measured an appearance potential for CHg from CH F of 14.6 0.6 eV, which would give an uncertainty of about 15 kcal mol" in the enthalpy of formation of methyl fluoride. However, a correlation of the enthalpy of formation from the atoms of the methyl fluorides and methyl chlorides indicates that the uncertainty can be reduced to 7 kcal mol". ... 

Fenarimol is thus a relatively weak inhibitor of aromatase in vitro. Consequently, a series of 5-substituted pyrimidine derivatives have been evaluated as aromatase inhibitors [134]. The most effective inhibitors were diarylpyrimidine methanols and diarylpyrimidine methanes containing electron-withdrawing substituents, especially chlorine atoms, at positions 4- and 4. The most potent, a-(4-chlorophenyl)-a-(4 -chlorophenyl)-5-pyrimidine-methane (5-[bis-(4-chlorophenyl)methyl]pyrimidine, LY56110, had an fC5o value of 55 nM in PMSG-treated rat ovaries [134]. This compound therefore appears to be a potentially useful aromatase inhibitor, but few other details have been published to date. 

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