IR absorption spectra of 1-aryl-3-pyrazolidones

An examination of the frequencies and intensities of the valence vibration bands of carbonyl groups established that the phenyl group interacts with the C=O group of 1-phenyl-3-pyrazolidone and its m- and p-tolyl derivatives in solution. It is assumed that the interaction is accomplished through the N₁ and N₂ atoms in the sp² state. 1-Phenylpyrazolidone derivatives are strongly associated in CC1₄ and CHCl₃ solutions. The association decreases on passing from CCl₄ to CHCl₃ solutions and when there are methyl groups in the ortho positions of the phenyl rings. The energy of association between the 1-phenylpyrazolidones and organic bases (acetonitrile, ethyl acetate, and dioxane), evaluated from the shift in _nh, is 1.36–3.5 kcal/mole. The frequencies and integral intensities of the bands of the C=O and NH groups in chloroform were measured.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1678–1682, December, 1970.     

Mass spectra of 2- and/or 6-alkyl-3-hydroxypyridines

The mass spectra of 2- and/or 6-aIkyI-3-hydroxypyridines were measured. The fragmentation processes include the loss of 1, 28 and 29 u and RCN from the molecular ions. Among the characteristic ions, the [M – 1]⁺ ions are the base peak for all of the ethyl-containing pyridines. According to a labelling study, the hydrogen on the β-caroon is the major contributor to the formation of [M – 1]⁺.     

Chemistry of 2-aryl-substituted 3-hydroxypyridines

Russian Chemical Bulletin -     

IR spectra and structure of 2- imino-1,3-dimethylbenzimidazolines

The fine structure of some N-substituted 2-imino-1,3-dimethyl-benzimidazolines is examined with the aid of IR spectroscopy. It is shown that the introduction of an alkyl or phenyl group into the imino group does not affect the C=N group or the imidazoline ring structure. In salts of 2-imino-1,3-dimethylbenzimidazoline and its N-substituted derivatives, the heterocyclic system has the benzimidazolium structure. The structure of 2-imino-1,3-dimethylbenzimidazolines in which the exocyclic nitrogen atom has electrophilic substituents which are conjugated with the heterocycle is characterized by a considerable contribution from dipolar forms, with the imidazole ring bearing a positive charge.Translated from Khimiya Geterotskilicheskikh Soedinenii, Vol. 6, No. 5, pp. 674–678, May 1970.     

Electronic structure and properties of 2- and 4-hydroxypyridines

The electronic structure of 2- and 4-hydroxypyridines and their chemical reaction capacity have been studied following the pattern of aromatic substitution in neutral, acid, and alkaline media within the framework of the Hückel approximation of the LCAO MO method. The reaction capacity indexes were calculated for both isolated and reacting molecules. It was shown that the calculated magnitudes agree well with previously recorded experimental data. The results obtained may serve to predict the direction of aromatic substitution reactions not yet studied within the hydroxypyridines series and their derivatives.The authors thank A. V. Tutkevich for kindly submitting the calculations program.     

Reaction of 1-chloroalkylheterocumulenes with diphenylguanidine. Synthesis and IR spectra of 2-aryl-2-trifluoromethyl-4-oxo-6-imino- and 2-aryl-2-trifluoromethyl-4,6-diiminoperhydro-1,3,5-triazines

1-Chloro-1-aryl-2,2,2-trifluoroethylheterocumulenes (isocyanates and carbodiimides) undergo regioselective cyclization with diphenylguanidine to give 2-aryl-2-trifluoromethyl-4-oxo-6-imino- and 2-aryl-2-trifluoromethyl-4,6-diiminoperhydro-1,3,5-triazines. An IR study of the 4-oxo-1,3,5-triazine derivatives showed a tendency for the formation of intermolecular aggregates or intramolecular hydrogen bonding, while a similar study of the 4-imino-1,3,5-triazine derivatives revealed that these compounds tend to undergo prototropic isomerization in the moiety.Institute of Organic Chemistry, National Academy of Sciences of Ukraine, 252660 Kiev, Ukraine. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 706–710, May, 1997.     

IR spectra and structure of 4-thiobarbituric acid derivatives

On the basis of data from the IR spectra of 4-thiobarbituric acid derivatives, and their deutero analogs, and similarly constructed model compounds, it was established that the investigated substances exist in the thione lactam form and form two types of associates through intermolecular hydrogen bonds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1416–1419, October, 1977.     

IR spectra and structure of biologically active carbulose preparation

The structural features of the carbulose preparation were studied by IR spectroscopy. It was shown that its base consists of a stable dimer of pyranose rings with a cellulose matrix, while its biological activity is determined by aprotic carboxylic COO^– groups in the side chains.Kiev Polytechnical Institute. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 3, pp. 387–390, May–June, 1991. Original article submitted March 4, 1991.     

Complete sets of structure fragments for interpreting IR spectra using IR databases

This paper studies the possibility of revealing various fragments (not given beforehand) in a structure by analyzing the structures selected from the database as a result of a retrieval by the IR spectrum of the compound; the fragments range from those with two nodes (e.g., C=O, C=C) to those with some limited number of connected nodes. It is shown that complete fragment sets reflecting the composition of the selected compound (fragment compositions) contain the information about the set of bonded fragments of the compound. Various factors affecting analysis of the compiled list of fragments are considered using a particular example. Different techniques for revealing structural information are discussed. Scientific and Technical Center of Chemical Informatics, Novosibirsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 2, pp. 368–378, March–April, 1996. Translated by L. Smolina     

Carbamic acid: molecular structure and IR spectra.

Infrared absorption spectra of mixed H2O, NH3 and 12CO2/13CO2 ices subjected to 1 MeV proton irradiation were investigated. The results of analyses of the spectra suggest formation of carbamic acid at low temperatures. The stability of this compound in the solid phase is attributed to intermolecular hydrogen bonding of the zwitter-ion (NH3+ COO-) structure.     

Synthesis of 2, 4, 6-trialkyl-3-hydroxypyridines

Summary A new method was proposed for the synthesis of 2,4,6-trialky1-3-hydroxypyridines by the reactions of 3,5-dialkyl-2-acylfurans with ammonia.