Infrared absorption spectra of pyridine N-oxide and benzoic acid complexes

The infrared absorption spectra in the 4000–1600cm⁻¹ region of some benzoic acid pyridine N-oxide derivative complexes are described.     

Absorption spectra of some pyridine and pyridine N-oxide derivatives in oleum

The absorption spectra of a number of pyridlne and pyridine N-oxide derivatives in media of different acidity functions have been investigated. The bathochromic shift of the shortwave absorption band in oleum is interpreted as a consequence of the addition of a proton to the conjugate acid. The formation of a hydrogen bond between the 3-hydroxy derivative of the heterocyclic compounds investigated and the oleum, appearing as a hypsochromic shift of the long-wave absorption band, has been detected. This phenomenon is absent in the case of the 2-methoxy derivative.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 963–966, July, 1973.     

Chemistry of heterocyclic N-oxides and related compounds 13. Acylamination of pyridine N-oxide by aniline,p-anisidine,and their N-p-tosyl derivatives

Acylamination of pyridine N-oxide by aniline, p-anisidine, and their tosyl derivatives was carried out in an alkaline medium in the presence of p-tosyl chloride. The reaction proceeds selectively with the formation of the corresponding 2-(N-p-tosyl) anilino- and 2-p-(N-p-tosyl)anisidino-pyridines. The reaction products were converted by acid hydrolysis into the corresponding 2-anilinopyridines.For communication 12, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 936–938, July, 1986.     

Ultraviolet absorption spectra of some pyridine and nicotine derivatives

Summary Comparison of the ultraviolet spectra of nicotine, N-methylanabasine, and their N-oxides shows that though the characters of the absorption of compounds containing the N-oxide group in the aromatic part of the molecule, on the one hand, and in the hydrogenated part, do not differ considerably, they are nevertheless sufficiently specific for a clear distinction to be drawn.For Communication 3 see [1].     

Microwave spectra of pyridine and monodeuterated pyridines. Revised molecular structure of pyridine

The microwave spectra of pyridine and its 2-D, 3-D and 4-D substituted species were reinvestigated. Nuclear quadrupole coupling and centrifugal distortion effects were considered also for the deuterated species resulting in improved values for the rotational constants of these species. Hereby more reliable information about the hydrogen positions could be obtained.     

Infrared crystal spectra of heterocyclic compounds. 1 . IR spectra of solid modifications of thiophene

The infrared spectra of the four solid modifications of thiophene have been studied. Absence of appreciable band shifts and solid state splitting, in going from the liquid to the solid phases, seems to indicate that the crystals of thiophene are disordered at least until the 4th solid modification becomes stable. Polarization measurements, carried out on the 4th phase, allow a tentative determination of the crystal structure at 100°K.     

Chemistry of heterocyclic N-oxides and related compounds. 11. Reaction of pyridine N-oxide with metal ketyls and benzophenone dianions

The reaction of pyridine N-oxide with metal ketyls of benzophenone was studied. It is shown that diphenyl(2-pyridyl)carbinol N-oxide is formed with the lithium and sodium derivatives of benzophenone, whereas diphenyl(2-pyridyl)carbinol is formed with the potassium derivative of benzophenone. Diphenyl(2-pyridyl)carbinol N-oxide is obtained in lower yields in the reaction of pyridine N-oxide with benzophenone dianions. Pyridine and 4,4- and 2,2-dipyridyls are simultaneously formed in all of the reactions.See [1] for Communication 10.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 655–658, May, 1979.     

Electronic spectra and structure of methyl derivatives of 4-nitropyridine N-oxide

The UV spectra of seven methyl derivatives of 4-nitropyridine N-oxide in ethanol have been examined. The electronic spectra were calculated by a modified INDO method. Transition energies, intensities and assignments were compared with UV spectra. Spectroscopic manifestations of intramolecular interaction indicate that methyl groups modify the electronic interaction between the N-oxide and NO₂ groups mainly through a steric strain.Department of Organic Chemistry, University of Economics, Pl-53342 Wroclaw, Poland. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 786–793, June, 2000.     

Studies on imidazole derivatives and related compounds. 2. Characterization of substituted derivatives of 4-carbamoylimidazolium-5-olate by ultraviolet absorption spectra

The representative mono- and dialkyl-substituted derivatives of 4-carbamoylimidazolium-5-olate (1) were synthesized unequivocally. On the basis of their spectral data for ultraviolet absorption spectra in acidic, basic and neutral solutions, we have found some spectral characteristics which make it facile to clarify the position of substituents.     

Chemistry of heterocyclic N-oxides and related compounds. 10. Reaction of pyridine N-oxide with 4-methyl- and 4-phenyl-substituted hantzsch esters

The corresponding dehydrogenation products were obtained in the reaction of diethyl 1,4-dihydro-2,4,6-collidine-3,5-dicarboxylates and diethyl 1,4-dihydro-4-phenyl-2, 6-lutidine-3,5-dicarboxylate with pyridine N-oxide. The reaction with dihydrocollidine is accompanied by simultaneous demethylation in the 4 position and methylation of the pyridine ring.See [1] for Communication 9.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 652–654, May, 1979.