Formamidic acid tautomers

As far as we are aware, this type of calculation has been performed for lactim and lactam tautomers of both 2- and 4-oxopyridines [(2), (3)] and for formamide (6a) and formimidic acid (6b) only (Schlegel et al., 1982 Scanlan et al., 1983). Since the calculations mentioned are expensive, one estimates the S a b,> value by comparison of the electronic energies calculated in the HF approximation only [(HF)8EAliq)L and even this has often been done by means of semiempirical methods [(CNDO/2i8 A B,... 

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