Three Vortices in Spaces of Constant Curvature: Reduction,Poisson Geometry,and Stability

This paper is concerned with the problem of three vortices on a sphere S² and the Lobachevsky plane L². After reduction, the problem reduces in both cases to investigating a Hamiltonian system with a degenerate quadratic Poisson bracket, which makes it possible to study it using the methods of Poisson geometry. This paper presents a topological classification of types of symplectic leaves depending on the values of Casimir functions and system parameters.     

Specific features of the CuI nanocrystal structure in photochromic glasses

Physics of the Solid State - The absorption spectra of CuI nanocrystals with an average radii of 5.3 and 6.2 nm in photochromic glass matrix have been studied in the temperature range 38–300...     

Spontaneous hexagon formation in photorefractive crystal with a single pump wave

A new scheme for spontaneous formation of hexagonal optical patterns in photorefractive crystals with dominant reflection gratings and a single pump wave is proposed and realized experimentally. It is shown theoretically that spontaneous hexagon formation results from random small-angle scattering of the pump wave inside the crystal. The threshold of spontaneous hexagon formation is found.     

Pyrimidines. 73. Synthesis of acetylpyrimidines

It is shown that the use of benzene as the solvent in the preparation of 2- and 4-acetylpyrimidines from cyanopyrimidines via the Grignard reaction makes this reaction a practical method for the preparation of pyrimidinyl ketones. Preparatively convenient methods for the preparation of 4-acetylpyrimidine from 4-ethylpyrimidine through the -oximino derivative and 5-acetylpyrimidine from 4,6-dichloro derivatives of pyrimidine are proposed.See [1] for communication 72.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 958–962, July, 1981.     

Tautomerism of derivatives of azines. 17. Effect of solvents on the position of the azinyl-ylidene tautomeric equilibrium of substitued azinylmethanes

The effect of solvents on the position of the azinyl-ylidene tautomeric equilibrium in series of azinylmethanes was studied. It was shown that an increase in the polarity of the solvent leads to stabilization of the ylidene tautomer; the sensitivity of the tautomeric equilibrium to the effects of the solvent depends on the form of the side fragment that undergoes tautomerization. It was concluded that stabilization of the ylidene tautomeric form by polar solvents is a general tendency in series of prototropic equilibrium of the azinyl-ylidene type as a whole.See [1] for Communication 16.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1668–1672, December, 1987.     

Pyrimidines

In the condensation of benzalbisurea with 1-methyl-3,5-diaminopyrazole the pyrimidine ring closes through the amino group of pyrazole in the 5 position to give 1-methyl-4-phenyl-3-benzalamino-6-oxo-4,5,6,7-tetrahydropyrazolo[3,4-d]pyrimidine. The latter is converted to 1-methyl-4-phenyl-3-amino-6-oxo-6,7-dihydropyrazolo [3,4-d]pyrimidine by dehydrogenation and subsequent hydrolysis of the benzylidene group.     

Tautomerism of azine derivatives. 5. Effect of the heteroatom on the keto-enol tautomerism of β-keto esters of the azine series

The effect of a nitrogen atom in various positions of the heteroaromatic ring on the ketol-enol equilibrium of 2-, 3-, and 4-pyridoyl-, 2- and 4-pyrimidoyl-, pyrazinoyl-, and 3- and 4-pyrazinoylacetic esters is examined. The anomalous effect of a nitrogen atom on the position relative to the tautomeric fragment is noted and is explained by interaction of the unshared pair of the nitrogen atom with the orbitals of the carbonyl group, which may lead to a decrease in the acceptor character of the azine substituent.See [1] for Communication 4. In Communication 4 [Khim. Geterotsikl. Soedin., No. 6, p. 823 (1980)] there is a misprint in the scheme that illustrates the tautomeric equilibrium -keto esters with the participation of protonated forms. See [16] for the corrected scheme.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 530–535, April, 1981.     

Polyfluorinated heterocyclic compounds

The treatment of 2-phenyl-4-carbomethoxy-6,7,8,9-tetrafluorobenz[f]oxazepin-1,3 (I), 3-benzamido-5,6,7,8-tetrafluorocoumarin (V), and α-benzamido-β-(2-hydroxy-3,4,5,6-tetrafluorophenyl)-acrylic acid (III) with a mixture of glacial acetic acid and a mineral acid gave (IV), the π-complex of 3-hydroxy-5,6,7,8-tetrafluorocoumarin (VII) and benzoic acid. Treatment of (IV) with acetic anhydride gave 3-acetoxy-5,6,7,8-tetrafluorocoumarin (VI) and benzoic acid. Treatment with diazomethane gave 3-methoxy-5,6,7,8-tetrafluorocoumarin (VIII) and methyl benzoate. IV was also obtained from an equimolar mixture of its components. A mechanism for the formation of IV from I is proposed.     

Synthesis and liquid-crystal properties of aryl esters of p-(5-alkyl-2-pyrimidinyl)benzoic acids

Aryl esters of p-(5-alkyl-2-pyriraidinyl)benzoic and p-(5-alkyl-2-pyrimidinyl)-benzoyloxybenzoic acids, which displayed nematic properties with broad ranges of the existence of a meso phase, particularly in the case of the diesters (up to 140–170C), were obtained. It is shown that the presence of a 2-phenyl group in the pyrimidine ring favors the development of a liquid-crystal state as compared with 5-phenylpyrimidines.DeceasedTranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1636–1639, December, 1988     

Pyrimidines

3-Arylbenzo[f]quinazolines were obtained by reaction in acetic or propionic acid of -naphthylamine, ammonia, and aromatic aldehydes containing an NR₂ or OH group. A mechanism is proposed for the formation of monoarylbenzo[f]quinazolines from the corresponding intermediate 1,3-diaryldihydrobenzo [f] quinazolines by acid cleavage of the C-aryl bond in the 1 position. This mechanism was confirmed experimentally by establishment of the fact of cleavage of 1,3-bis (p-methoxyphenyl)-1,2-dihydrobenzo[f] quinazoline when the acidity of the medium is increased; 3-(p-methoxyphenyl) benzo [f] quinazoline and anisole were obtained in the reaction products. Condensation in the presence of formic acid gave -arylidene-N-formyl--naphthylamines rather than arylbenzo [f] quinazolines.See [1] for communication LXIV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1265–1271, September, 1978.