Synthesis and pyrolysis of (cyclobutylmethyl)trimethylsilane

Russian Chemical Bulletin -     

Synthesis of Sulfur-Containing Bis-Terpenoids Based on Monoterpene Oxides

Ethanedithiol and di(mercaptoethyl)sulfide react regio- and stereoselectively with (+)-3-carene and -hydroxy(-)--pinene -oxides in the presence of sodium ethoxide to give the corresponding bis- and tris-sulfides with two terpene fragments     

Ethylene polymerization and copolymerization with hexene-1 on supported metallocene catalysts based on (C<Subscript>5</Subscript>H<Subscript>5</Subscript>)<Subscript>4</Subscript>Zr and methylaluminoxane

New supported metallocene catalysts based on tetrakis(cyclopentadienyl)zirconium + methylaluminoxane (MAO) were prepared and tested for ethylene polymerization and copolymerization with hexene-1. It was shown that silica gel of the Davison 952 brand is the best support for such catalysts. The maximum catalyst activity was achieved on the support impregnated with the (C₅H₅)₄Zr-MAO complex. The addition of hexene-1 into the liquid phase resulted in acceleration of polymerization and an increase in the product yield. The morphological, rheological, and other properties of polymers and copolymers were studied. The test catalytic system can be used for manufacture of low-, medium-, and high-density polyethylenes with various stress-strain characteristics.     

Dosage par activation neutronique d'impuretes dans l'argent tres pur avec separation des elements par extraction

Résumé Nous avons élaboré une méthode d'analyse par activation neutronique de 24 microimpuretés dans l'argent. Pour éliminer la matrice et séparer les impuretés, nous avons utilisé l'extraction. Nous avons évalué théoriquement et vérifié expérimentalement l'effet d'écran des échantillons d'argent sur le flux de neutrons.     

BF3-catalyzed addition of thiols to (+)-camphene

BF₃-catalyzed addition of some thiols to (+)-camphene was examined. Reactions with aromatic thiols and hetaryl thiols result in terpene sulfides of camphene or bornane structure in accordance with the Markovnikov’s rule, whereas with remain thiols the reaction proceeds against the Markovnikov’s rules preserving the original structure of the molecule.     

Study of “Racemic Compound-Like” Behavior of Diastereomeric Mixture of Pinanyl Sulfoxides by X-Ray Diffraction,IR Spectroscopy,and DFT Calculations

Abstract

The oxidation of a β-hydroxysulfide in the pinane series by use of m-chloroperbenzoic acid resulted in the formation of the corresponding β-hydroxysulfoxide as a mixture of two diastereomers in 4:5 ratio. According to single-crystal X-ray diffraction (XRD) results, it is established that the diastereomeric mixture of sulfoxides crystallizes in the “racemic compound-like” manner under formation of asymmetric dimers through S=O··H–O interactions. This asymmetric dimer formed from diastereomeric molecules is a structural unit in both crystal modifications, the triclinic and the monoclinic one. The behavior of the diastereomeric mixture of pinane derived sulfoxides in crystals, melts and in tetrachloromethane solutions was studied by IR spectroscopy. The density functional theory (DFT) method with 6-31G (d, p) basis set was used to calculate the optimized geometrical parameters and vibrational frequencies of different associates in solutions. The calculated vibrational frequencies are compared with experimental IR spectra.     

Addition of thiols to (-)-carvone

Polyfunctional thioterpenoids were formed in the presence of a Lewis-acid catalyst by reaction of (-)-carvone with thiols that involved the endocyclic double bond and the carbonyl.Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 393–395, September–October, 2004.     

trans-Diepoxy Derivative of Limonene. Synthesis, Structure, and Products of Oxirane Ring Opening with Sulfur-Containing Reagents

Pure trans-diepoxy derivative of limonene was synthesized for the first time. Its reactions with sulfur-containing nucleophiles in basic medium resulted in formation of polyfunctional derivatives of the menthane series, 2,9-bis(R-thio)-trans-p-menthane-1,8-diols.