Crystal and molecular structure of 2-phenyl-2-thiono-5,6-(4′,5′-dimethylbenzo)-1,3,2-dithiaphosphepine and 2-methoxy-2-oxo-5,6-benzo-1,3,2-dioxaphosphepine

A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Branch, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 31, No. 5, pp. 75–80, September–October, 1990.     

Regio- and stereoselectivity of the reactions of pyridinium and picolinium salts and ylids with nitriles containing a nucleofugic group

The reaction of pyridinium, 2-picolinium, and 3-picolinium ylids with tetracyanoethylene, ethoxymethylenemalononitrile, and (dimethylthio)methyl-enecyanamide in the presence of organic bases proceeds regio- and stereo-selectively to give substituted pyridinium 1,4-ylids, 2-(2-propen-1-ylidene)-1,2-dihydropyridines, and 5-(1-pyridino)pyrimidin-4-olates, respectively. The reaction of 1-phenacylpyridinium bromide and tetracyanoethylene leads to 1-phenacylpyridinium tricyanoethenolate.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 939–942 April, 1990.     

Stereoselective transformation of 1,3-dithia-4-cyclohexene enaminonitriles into substituted 3,4-trans-1,2,3,4-tetrahydropyridine-6-thiolates with pyridinium ylides

4-Amino-6-aryl-2,2-dialkyl-5-cyano-1,3-dithia-4-cyclohexenes react with pyridinium ylides in thermodynamically controlled conditions with the formation of 4-aryl-2-oxo-thioxo)-3-(1-pyridino)-5-cyano-3,4-trans-1,2,3,4-tetrahydropyridine-6-thiolates. Arylidenecyanothioacetamides act as intermediates of this recyclization, and the corresponding pyridine-6-thiolates were obtained from them by an independent method. The synthesized hydrogenated pyridine-6-thiolates are in the half-chair conformation with a trans-diaxial position of the 3-H and 4-H hydrogen atoms.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1082–1086, August, 1991.     

Crystal and molecular structure of aroyl- and acetylhydrazones of acet- and benzaldehydes

Aroyl- and acetylhydrazones of acet- (I) and benzaldehydes (IV) and benzoylhydrazones of acet- (II) and benzaldehydes (III) were studied by x-ray structural and quantum-chemical methods in order to establish their structures. Compund (I) was the EEZ structure in the crystal. Calculations and spectral data showed that the EEE form occurs in nonpolar solvents and in the gas phase. According to crystallographic data molecules (I)–(IV) are the E-isomers (relative to the N-N bond) and the hydrazone fragments are planar. Intermolecular N-H...O H-bonds from in the crystals. The data obtained suggest that the majority of acylhydrazones are conformationally rigid on dissolution although exceptions do occur. Apparently the reasons for the difference of acetyl- and benzoylhydrazones in electrocarboxylation reactions are electronic and not steric factors.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 75–81, January, 1991.     

New method for the synthesis of 6-amino-4-aryl-3,5-dicyano-3,4-dihydropyridine-2(1H)-thiones by recyclization of 4-aryl-2,6-diamino-4H-thiopyranes

Ammonium 6-amino-4-aryl-3,5-dicyano-1,4-dihydropyridine-2-thiolates were synthesized by recyclization of 4-aryl-2,6-diamino-3,5-dicyano-4H-thiopyranes in the presence of organic bases. On acidification of the products, the corresponding substituted 3,4-dihydropyridine-2(1H)-thiones were obtained which were used in the synthesis of 2-alkylthio-1,4-dihydropyridines, bis-(pyridyl-2)disulfides and thieno[2,3-b]pyridines.Deceased.T. G. Shevchenko Lugansk State Pedagogical Institute, Lugansk 348011. N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 909–914, July, 1997.     

A new method for the synthesis ofN-methylmorpholinium 4-aryl-5-cyano-2-oxo-1,2,3,4-tetrahydropyridine-6-thiolates and their properties

N-Methylmorpholinium 4-aryl-5-cyano-2-oxo-2-oxo-1,2,3,4-tetrahydropyridine-6-thiolates were obtained by the condensation of aromatic aldehydes, cyanothioacetamide, and Meldrum's acid in the presence ofN-methylmorpholine. They were then used in the syntheses of substituted 6-alkylthio-3,4-dihydropyridin-2(1H)-ones and 4,5-dihydrothieno[2,3-b]pyridin-6(7H)-ones. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1852–1856, October, 1997.     

Synthesis and molecular and crystal structures of triethylammonium 2,2,5-triphenyl-1,3,2,5-dioxaboratophosphorinane hydrate

Organic and Physical Chemistry Institute, Kola Scientific Center, Russian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 2, pp. 133–137, March–April 1992.     

Local Vibrations of Oxygen-Containing Thermal Donors in Germanium

The vibrational absorption bands associated with some types of double thermal donors (TD) in Ge enriched with the oxygen isotopes ¹⁶O and ¹⁸O have been identified. The thermal donors were formed during heat treatment of Ge:O crystals at 300 and 350°C. Absorption spectra were measured at room temperature and at 10 K. The formation of the thermal donors was accompanied by the appearance of three absorption bands, which in the Ge:¹⁶O spectra at room temperature are located at 600, 740, and 780 cm^–1. In low-temperature measurements, the bands at 600 and 780 cm^–1 exhibited splitting into series of narrow lines (up to 9) associated with some types of thermal donors (TD1–TD9). The absorption spectra measured at 10 K after different cooling conditions display bistability of the first four types of thermal donors (TD1–TD4). In the samples cooled by illumination with light in the region of frequencies of the fundamental absorption of Ge, pairs of lines are observed that belong to the bistable thermal donors in the helium-like configuration of double donors (DD). After cooling the samples in the dark, these pairs of lines are replaced by three new bands, which belong to local vibrational modes of bistable thermal donors in the low-energy neutral configuration. Based on the isotopic shift of the local vibrational modes of the thermal donors in Ge:¹⁶O and Ge:¹⁸O, a rigorous proof of the oxygen atoms entering into the composition of thermal donors is obtained.     

Investigation of a wake decay behind a circular disk in a hydro channel at high Reynolds numbers

LDA and PIV techniques were used to study the decay of an axisymmetrical turbulent wake originated downstream an immobile disk in a water flume for Reynolds numbers Re = 1.5?2.4?10⁵. Data were compared with experiments performed with a set of thermo-anemometers behind a disk in a wind tunnel at lower Reynolds numbers (Re = 1.3?2.6?10⁴). Observations for a new range of Reynolds number confirmed that the velocity distribution in the disk wake keeps self-similarity. The decay of a wake by the power law ?2/3 in the presented experiments remains until the maximum deficit of velocity becomes comparable with the turbulent pulsation level in the free-stream (less than 2 %).