Yu. P. Kitaev

Stereochemistry and dipole moments of ?,?-Unsaturated heterocyclic ketones

The dipole moments of eight α,β-unsaturated aromatic and heterocyclic aldehydes and ketones in dioxane solution were measured. The moments of the syn and anti conformations were calculated by vector-additivity schemes. The effect of the conformation on the moment of the C=O group was taken into account. The charge distribution was calculated by the Pariser-Parr-Pople method in order to estimate the polarization of the C=C bond.

Structures and reactivities of nitrogen-containing derivatives of carbonyl compounds: XXXIII. UV spectra and structures of 4-benzylideneamino-1,2,4-triazoles

A number of products of the condensation of aminotriazole with substituted benzaldehydes were synthesized. Their UV spectra in ethanol and concentrated sulfuric acid are presented. The change in the UV spectra on passing from one solvent to another is explained by the change in the conjugation of the N-N bond. The basicities of the nitrogen atoms were compared by the Pariser-Parr-Pople method.

Conformation of thiophene analogs of chalcone containing a naphthalene ring

It has been shown on the basis of dipole moment and IR spectroscopic measurements of thiophene-naphthalene analogs of chalcone that the latter exist in the s-cis form in solutions and have a trans configuration of the substitutents at the double bond and a definite position of the thiophene ring.

Synthesis and some properties of 2-methylphthalazone hydrazones

The reaction of 1-chloro- and 1,4-dichloro-2-methylphthalazinium salts with hydrazine leads to the formation of hydrazones and azines of the corresponding 2-methylphthalazones, the ratio of which depends on the reaction conditions. Symmetrical azines of 4-substituted phthalazones exist in the EEE form, while azines of 2-methyl-4-substituted phthalazones exist in the ZEZ form.

Research in pyrazolidine chemistry

An increase in the resistance of the N-N bond to hydrogenolysis on Raney nickel in alkaline media is observed not only for 1,2,4-trisubstituted 3,5-dioxopyrazolidines but also for other types of 3,5-dioxopyrazolidines that are capable of enolization. 3,5-Dioxopyrazolidines that are capable of forming betaines also do not undergo hydrogenation in neutral ethanol. The use of the potentiometric method of Sokolskii and Druz′ made it possible to establish very slight adsorption of the enolates and betaines on the catalyst surface. The decrease in adsorbability is explained by a decrease in the effective charges on the nitrogen atom of the heteroring; this is in agreement with the results of calculations of the enolate and enol by the Pariser-Parr-Pople method. An assumption regarding the greater aromatic character of the enolate as compared with the enol is expressed on the basis of a comparison of the bond lengths.

Research in the chemistry of pyrazolidine

The rate of hydrogenolysis of 3,5-dioxopyrazolidines at the N-N bond is determined by the number, position, and nature of the substituents in the heteroring. The introduction of a phenyl group into the 1 and 2 positions increases the rate of hydrogenation, while a phenyl group in the 4 position lowers it. On the other hand, an alkyl substituent in the 1 and 2 positions lowers the rate of hydrogenation, while an alkyl substituent in the 4 position increases it. It is assumed that the effect of substituents is a consequence of an increase or decrease in the adsorption of a molecule by the β-dicarbonyl or hydrazine fragments; this is in agreement with the results of calculation of the charges on the heteroring atoms. The hydrogenation of 4alkyl-1, 2-diphenyl-3,5-dioxopyrazolidines is limited by their activation, while the hydrogenation of the 4-phenyl derivative is limited by the activation of hydrogen.

The structure of some benzylideneamino-pyridinium iodides

The UV, IR, and PMR spectra of a number of m- and p-substituted N-(benzylideneamino)-pyridinium iodides confirm the structure of hydrazonium compounds proposed for them previously. On the basis of physicochemical data, a hypothesis has been put forward of the participation of the pyridinium ring in an intramolecular interaction of the conjugation type. Charge-transfer bands are observed in the UV spectra of some of these compounds.