87775-66-4Relevant academic research and scientific papers
Hydrazine-hydrazone tautomerism in phenylhydrazinopyrimidones
Wright
, p. 1037 - 1042 (1983)
4-Phenylhydrazino-2-pyrimidone and its 1-methyl analog have been shown by 1H nmr to exist in interconverting hydrazine and hydrazone tautomers in deuteriodimethylsulfoxide solution. Solvent effects indicate that increasing solvent polarity favors the hydrazine forms. In contrast, the 3-methyl analog occurs exclusively as the hydrazone. The hydrazone forms of the parent and 1-methyl derivatives appear to adopt the syn rotamers as a result of intramolecular hydrogen bonding. Variable temperature studies showed relatively high free energy barriers to tautomerization in these compounds, resulting both from solvation and intramolecular hydrogen bonding. The 1H nmr spectra of 1-methyl-4-hydrazino-2-pyrimidone suggest that it exists predominately as the hydrazone in deuteriodimethylsulfoxide:deuteriochloroform solution, although the barrier to tautomerization is similar to those for the phenylhydrazino compounds.
