92916-85-3Relevant academic research and scientific papers
Tautomerism in a Series of Products of Condensation of Fluorinated 1,3-Diketones with Aroylhydrazines
Yakimovich,Zerova,Zelenin,Alekseev,Tugusheva
, p. 370 - 374 (2007/10/03)
The condensation of aroylhydrazines with 1,3-diketones CH3COCH2COR, where R is a perfluoroalkyl group, proceeds on the acetyl carbonyl. Condensation products exist in solutions in the form of two tautomeric forms: conjugated enhydrazinic and 5-hydroxypyrazolinic forms. The open tautomer is favored by an enlargement of the perfluoroalkyl radical chain, the introduction of electron-donating substituents into the aromatic ring of the hydrazine component, and the use of basic dipolar solvents. The reactions of aroylhydrazines with trifluoroacetylpinacolin occur predominantly on the trifluoroacetyl function. Trifluoroacetylpinacolin derivatives in solutions exist as mixtures of hydrazonic and 5-hydroxypyrazolinic forms. The tautomeric equilibrium is shifted to the cyclic form when electron-withdrawing substituents are introduced into the aromatic ring and nonpolar solvents are used.
TAUTOMERISM IN THE SERIES OF BENZOYLHYDRAZONES OF ALIPHATIC β-DICARBONYL COMPOUNDS
Yakimovich, S. I.,Nikolaev, V. N.,Blokhtina, S. A.
, p. 1247 - 1254 (2007/10/02)
It was shown by PMR spectroscopy that the benzoylhydrazones of aliphatic β-dicarbonyl compounds exist in solutions as tautomeric mixtures of the cyclic 5-hydroxypyrazoline and open forms.The latter are represented by the hydrazone or enehydrazine form or their combination, depending on the structure of the β-dicarbonyl component and the solvent.Increase in the size of the terminal substituent at the C=N bond displaces the equilibrium toward the cyclic 5-hydroxypyrazoline form, and the introduction of strong electron-withdrawing substituents at the C=N bond favors the hydrazone and cyclic forms.The benzoylhydrazones of symmetrical β-diketones have a cyclic 5-hydroxypyrazoline structure.
