Vanadium-catalyzed pinacol coupling reaction in water

A catalytic pinacol coupling using water as a solvent was performed by a catalytic amount of vanadium(III) chloride and metallic Al as a co-reductant. A combination forms a binary catalytic system, being in sharp contrast to the reaction in organic solvent, which requires a chlorosilane as an additive. Various aromatic aldehydes underwent the reductive coupling to give the corresponding 1,2-diols in moderate to good yields.     

On the Geometry of Holomorphic Flows and Foliations Having Transverse Sections

One of the main tools in the study of real foliations of codimension one is the use of transverse sections. Given a codimension one real foliation on a compact manifold there is always a transverse circle and the topology of its embedding into the ambient manifold often has important consequences on the global behavior of the foliation; as in Haefliger’s Theorem and Novikov’s c7ompact leaf theorem for instance.     

Raman scattering in low wavenumber region as a new probe to structural properties of microcrystalline silicon

The structural properties of microcrystalline silicon (μc-Si) are studied by Raman scattering. It is found that the intensity of each Raman band closely correlates with the absorption coefficient in the interband region and that the Raman band at ca. 150 cm^?1 is a sensitive probe to randomness of Si-Si bonding structure in μc-Si.     

Mode of oxidations of organosulfur compounds: Example of nucleophilic oxygenations of thiolsulfinates

Two types of oxygenative oxidations (Nucleophilic and Electrophilic Oxidations) of sulfur atom are proposed and a typical mode of nucleophilic oxidation is shown with a few unsymmetrical thiolsulfinates.     

The chemical form and acute toxicity of arsenic compounds in marine organisms

A method for the separation and identification of inorganic and methylated arsenic compounds in marine organisms was constructed by using a hydride generation/cold trap/gas chromatography mass spectrometry (HG/CT/GC MS) measurement system. The chemical form of arsenic compounds in marine organisms was examined by the HG/CT/GC MS system after alkaline digestion. It was observed that trimethylarsenic compounds were distributed mainly in the water-soluble fraction of muscle of carnivorous gastropods, crustaceans and fish. Also, dimethylated arsenic compounds were distributed in the water-soluble fraction of Phaeophyceae. It is thought that most of the trimethylated arsenic is likely to be arsenobetaine since this compound released trimethylarsine by alkaline digestion and subsequent reduction with sodium borohydride. The major arsenic compound isolated from the water-soluble fraction in the muscle and liver of sharks was identified as arsenobetaine from IR, FAB Ms data, NMR spectra and TLC behaviour. The acute toxicity of arsenobetaine was studied in male mice. The LD₅₀ value was higher than 10 g kg⁻¹. This compound was found in urine in the non-metabolized form. No particular toxic symptoms were observed following administration. These results suggest that arsenobetaine has low toxicity and is not metabolized in mice. The LD₅₀ values of other minor arsenicals in marine organisms, trimethylarsine oxide, arsenocholine and tetramethylarsonium salt, were also examined in mice.     

Relative stability of η-cyclopentadienyl(olefin)ruthenium cations: The first estimation of the nature of the Ru-olefin bond

Relative stability in coordination of substituted styrene derivatives to [Ru(η-C₅H₅)(dtpe)]⁺ (dtpe = 1,2-bis(di-p-tolylphosphino)-ethane) was determined by NMR spectroscopy to reveal unusually weak substituent dependency of the stability.     

(6Li,d) reactions on 24Mg and 26Mg at 73 MeV

The ^{24, 26}Mg(⁶Li, d)^{28, 30}Si reactions have been studied at 73 MeV bombarding energy. The angular distributions were analyzed with exact finite-range distorted wave Born approximation calculations assuming a direct α-cluster transfer. Extracted spectroscopic strengths leading to low-lying levels of ²⁸Si and relative spectroscopic strengths between transitions to ²⁸Si and ³⁰Si ground states are consistent with those previously obtained by several α-transfer reactions. Many strongly populated levels have been observed at E_x ? 10 MeV for ²⁸Si. A marked similarity was found between the deuteron spectrum and the ²⁴Mg(α, α)²⁴Mg excitation function in this excitation energy region. A brief comparison of the present α-transfer results with previous two-nucleon transfer data leading to ^28,30Si is also presented.     

High field magnetization of Y2Co7 and YCo3 hydrides

The magnetization curves for the Y₂Co₇H_x and the YCo₃H_x systems have been measured at 4.2 K in the pulsed high magnetic fields up to 280 kOe. The metamagnetic transition is observed in the β and the γ hydrides except for Y₂Co₇H₃ and YCo₃H₁, which is interpreted in terms of the itinerant electron metamagnetism.