Studies of the tautomerism and geometrical isomerism of nitrogen-containing derivatives of carbonyl compounds I. Polarographic study of the transformations of some phenylhydrazones in methanol

Summary

• 1. The polarographic method was employed in a study of the tautomeric and stereoisomeric transformations in alcoholic solutions of the phenylhydrazones of acetone, methyl ethyl ketone, methyl isopropyl ketone, cyclohexanone and benzaldehyde; the ethylphenylhydrazone of acetone was also studied.

• 2. It was shown that in alcoholic solution phenylhydrazones are generally capable of existing in three tautomeric forms, each of which in turns can be present as $yn- and anti-isomers. On dissolution in alcohol the tautomeric equilibrium

  

  Is shifted to the side of the azo form.

• 3. The half-wave potentials of the tautomers and stereoisomers of the various phenylhydrazones were determined, and the energies of the reciprocal transformations were calculated from the data obtained.

• 4. It was established that the phenylhydrazones of acetone, methyl ethyl ketone, methyl isopropyl ketone and cyclohexanone and the ethylphenylhydrazone of acetone possess the enhydrazone structure in the free state.