| Affiliation: | (1) St. Petersburg State University, St. Petersburg, 198504, Russia;(2) Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg, Russia;(3) Research Test Center of Medical and Biogical Protection of the State Research Testing Institute of Military Medicine of the Defence Ministry of the Russian Federation, St. Petersburg, Russia |
| Abstract: | Condensation products of aroylacetic aldehydes with hydrazides of thioglycolic, 3-mercaptopropionic and 2-mercaptobenzoic acids exist in cyclic 1,3,4-thiadiazine, 1,3,4-thiadiazepine, or 1,3,4-benzothiadiazepine forms arising at the intramolecular addition of the mercapto group to the C=N bond of the initially formed hydrazone tautomer. The appearance of an alternative 5-hydroxy-2-pyrazoline form is favored by introduction of a strong electron-acceptor substituent into the aromatic ring of the 1,3-ketoaldehyde or by going over to benzoylacetone derivatives. In solutions the derivatives of aroylacetic aldehydes and of benzoylacetone show no tendency to tautomeric transition into linear hydrazine or enhydrazine forms. |
