18995-90-9Relevant articles and documents
RING-CHAIN AND RING-LINEAR-RING TAUTOMERISM IN THIOCARBONOHYDRAZONES
Alekseev, V. V.,Zelenin, K. N.,Terent'ev, P. B.,Lashin, V. V.,Khorseeva, L. A.,Bulakhov, G. A.
, p. 491 - 501 (2007/10/02)
The structure of the thiocarbonohydrazones of monocarbonyl compounds was studied by 1H and 13C NMR spectroscopy in solutions and by mass spectrometry in the gas phase. In solutions, irrespective of the substitution in the aromatic ring and in the hydrazine fragment, the thiocarbonohydrazones of aromatic aldehydes exist in the linear form, whereas the 2- and 5-substituted thiocarbonohydrazones of ketones are susceptible to ring-chain tautomerism: Thiocarbonohydrazone - 4-amino-1,2,4-triazolidine-3-thione. Those not having substituents at the nitrogen atoms are susceptible to ring-linear-ring equilibria: Hexahydro-1,2,4,5-tetrazine-3-thione - thiocarbonohydrazone - 4-amino-1,2,4-triazolidine-3-thione. In the gas phase under conditions of high vacuum, according to the mass spectra, the coexistence of four tautomeric forms (linear, tetrazine, triazolidine, and 2-hydrazino-1,3,4-thiadiazolidine) is possible in individual cases.
