Electrochemically induced formation of organomercury compounds

A procedure for the alkylation of metallic mercury by (dimethylglyoximato)butylcobalt(III) electrochemically generated in the presence of butyl bromide is proposed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 309–312, February, 1994.     

分子内环加成的甾体全合成

近年来,分子内环加成反应已广泛用于甾体化合物全合成,其主要一步是由取代的苯并环丁烯热裂而成的5,6-二亚甲基-1,3-环己二烯发生区域专一和立体选择性的环加成反应,构成甾体骨架。现在用此法已合成了一系列消旋和光学活性的甾体化合物。     

Crystallization of chiral compounds. 1. Spectroscopic,thermochemical, and crystallographic investigation of homochiral and racemic glycidyl p-toluenesulfonate

Crystalline specimens of homochiral and racemic glycidyl p-toluenesulfonate were studied by IR spectroscopy, differential scanning calorimetry, and X-ray diffraction analysis. The melting phase diagram of glycidyl p-toluenesulfonate was constructed. The stacking effect in the crystals of the racemic sulfonate is responsible for a more dense molecular packing, with the result that a heterochiral type of crystallization becomes more favorable.     

Some Conversions of Thiazoline Carboxylic Acid Esters

We have carried out solvolysis of the previously described ethyl esters of 3-methyl(aryl)-4-methyl-2-thioxothiazoline-5-carboxylic acids, leading to the corresponding acids without breaking down the heterocycle. We synthesized a series of novel esters from the latter by treatment with dimethyl sulfate or reactive halides. Of these, only in the case of the ethyl ester of 3,4-dimethyl-2-thioxothiazoline-5-carboxylic acid did we obtain the hydrazinolysis product (the hydrazide), from which we synthesized novel hydrazones by treatment with aldehydes and ketones.     

Emanation Thermal Analysis of SiC Based Materials

Results of emanation thermal analysis (ETA) characterizing microstructure changes of SiC based materials during heat treatment in argon are demonstrated. This method made it possible to reveal fine changes of the texture of SiC nano-sized powders, SiC micro-sized powders and SiC whiskers under in situconditions of the heating. ETA curves can serve as fingerprints of the respective samples.This revised version was published online in November 2005 with corrections to the Cover Date.     

Composition catalysts of ethylbenzene oxidation based on bis(acetylacetonato)nickel(ii) and phase transfer catalysts as ligands 1. Macrocyclic polyethers

The addition of the macrocyclic polyether 18-Crown-6 (18C6) increases the selectivity of oxidation of ethylbenzene to -phenylethylhydroperoxide (PEH) in the presence of Ni(acac)₂. The initial oxidation rate, selectivity and degree of conversion of ethylbenzene to PEH are greater than those catalyzed by Ni(acac)₂ only. The efficiency of the macrocyclic ligand as an activator of Ni(acac)₂ exceeds that of monodentate donor ligands. The high selectivity of the process is due to both the primary Ni(acac)₂ · 18C6 complexes and the products of their transformation in the course of oxidation. The mechanism of ethylbenzene oxidation catalyzed by Ni(acac)₂ · 18C6 complexes is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1406–1411, August, 1994.     

Electronic structure and the hydrogen-shift isomerization of hydrogen nitryl HNO2

Summary Electronic structure of hydrogen nitryl HNO₂, a yet not identified entity, and the path of its possible isomerization totrans-HONO have been investigated byab initio SCF and MRD-CI computations using the 6-31G** basis set. HNO₂ isC _2v -symmetric and its ground state (¹ A ₁) is less stable thantrans-HONO by 66 kJ/mol (with the SCF vibrational zero-point energy correction). The lowest two excited singlet states (¹ A ₂ and¹ B ₁) are nearly degenerate, their vertical excitation energies being predicted to be 4.8 eV. The isomerization path is traced by the CASSCF procedure and the activation barrier height is evaluated by the CI treatment. HNO₂ in its ground state isomerizes totrans-HONO by maintaining the planar (C _s-symmetric) structure. The activation energy is calculated to be 171 kJ/mol, which is clearly lower than the calculated H-N bond energy (253 kJ/mol). The transition state seems to be more adequately described as an interacting system of proton and the nitrite anion rather than as a pair of two fragment radicals.     

Synthesis and structure of novel derivatives of thieno[2,3-b]thiocine. An unusual product of intramolecular cycloaddition of 2-homomethallylthio-5-methyl-3-thiophenecarbonitrile oxide

9-Methyl-3,3a,4,5-tetrahydro-6H-thieno[2,3-b]thiocino[4,5-c]isoxazole and 9-hydroxyimino-2-methyl-7-methylene-6, 7,8,9-tetrahydro-5H-thieno[2,3-b]thiocine have been prepared for the first time by the oxidation of 2--alkenylthio-3-thiophenecarbaldoximes with NaOCl. X-ray structural investigations of thieno[2,3-b]thiocine and 2-homomethallylthio-5-methyl-3-thiophenecarbaldoxime have been carried out.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1262–1266, July, 1993.     

The preparation and X-ray structural study of complexes that catalyze isocyanate cyclotrimerization

A 11-complex of trinitrophenol with benzyldimethylamine (1) and a 111-complex, the product of the interaction of benzyldimethylamine, glycidyl phenyl ether, and phenol (2), have been synthesized and characterized by means of X-ray analysis. Complex1 is a precursor for the catalysts of selective isocyanate cyclotrimerization, while complex2 is one of those catalysts. In the crystal structure complex1 forms H-bonded cationic-anionic aggregates with proton transfer from phenol to the N-atom of the tertiary amine. Complex2 crystallizes as a monohydrate (2a) with a strong H-bond between the quaternary ammonium and phenolic components, and exists in crystals in the form of globular H-bonded dimeric hydrates. Possible pathways of dissociation of complex2a are discussed. The data obtained may be used as a basis for further interpretation of the regularities of cyclotrimerization of isocyanates catalyzed by complexes of this type.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No 1, pp. 92–97, January, 1993.