Pyrimidines. 72. Synthesis and some properties of 5-amino-2-r-4,6-diphenylpyrimidines and the products of their transformations

The corresponding 5-aminopyrimidines were obtained by reduction of 2-substituted 5-nitro-4,6-diphenylpyrimidines, and reactions involving the amino group were studied. A Schiff base was obtained, and acetylation and diazotization reactions were carried out. The corresponding diazonium salts were converted to 2-dimethylamino-5-hydroxy-4,6-diphenylpyrimidine and 5-azido-2-methoxy-4,6-diphenylpyrimidine. 2-Methoxy-4-phenyl-5H-pyrimido[5,4-b]indole was obtained by photocyclization of the latter.See [1] for Communication 71.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1278–1282, September, 1980.     

Pathways of formation of spiropyrimidinebarbituric acids

Conclusions The selection between the two possible schemes of closing of the 2-oxohexahydropyrimidine ring in favor of the carbocation mechanism was made on the basis of mass spectrometric analysis of spiropyrimidinebarbituric acid, produced using monolabeled urea-N¹⁵.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1637–1638, July, 1970.     

Proof of the structure of 1-tosyl-5-(2′-nitrovinyl)imidazole

The structure of 1-tosyl-5-(2′-nitrovinyl)imidazole was established on the basts of its NMR spectrum [by means of tris(dipivaloylmethanato)europium as the “shift reagent”] and from the magnitude of the dipole moment.     

A Nonholonomic Model of the Paul Trap

In this paper, equations of motion for the problem of a ball rolling without slipping on a rotating hyperbolic paraboloid are obtained. Integrals of motions and an invariant measure are found. A detailed linear stability analysis of the ball’s rotations at the saddle point of the hyperbolic paraboloid is made. A three-dimensional Poincaré map generated by the phase flow of the problem is numerically investigated and the existence of a region of bounded trajectories in a neighborhood of the saddle point of the paraboloid is demonstrated. It is shown that a similar problem of a ball rolling on a rotating paraboloid, considered within the framework of the rubber model, can be reduced to a Hamiltonian system which includes the Brower problem as a particular case.     

Optimization of the structure of an optical fiber polarizer with a metal film at a wavelength of 980 nm

The dependence of the extinction ratio of a 980-nm fiber polarizer with an Al film on the thickness of magnesium fluoride buffer layer has been experimentally and theoretically investigated. At the optimal thickness of the buffer layer, h _b = 0.078 (normalized to the wavelength), extinction ratios of 23 and 41 dB were obtained for polarizers having fiber shell residual layers of 2.01 and 1.607 μm, respectively. The optimal thin-film structure is determined, which will make it possible to design polarizers with extinction ratios up to 100 dB.     

The Initial Stages of the Onset of a Corona Discharge in a Wet Oxide Layer During the Passage of a High Voltage Current

Russian Physics Journal - The physical and chemical processes occurring in non-metallic inorganic porous coatings during the passage of a high-voltage alternating sinusoidal current through the...