Carbon-13 Separation by IRMPD of mixtures of C2F6 and Br2

The infrared multiple-photon decomposition of mixtures of C₂F₆ and Br₂ has been examined as functions of various experimental parameters. Carbon-13 was found to be enriched in the main product CF₃Br; the maximum enrichment factor was 35. The combination of this process with the IRMPD of CF₃Br provides a closed chemical cycle for efficient carbon isotope separation     

Preparation and structural determination of methyl 3-C-p-tolylsulfonyl-2-C-p-tolylthio-β-d-glucopyanoside derivatives and their 5a-carba-dl-analogs having non-chair conformation in solutions

Methyl 4,6-O-benzylidene-2,3-dideoxy-3-C-p-tolylsulfonyl-2-C-p-tolylthio-β-d-glucopyranoside and its 5a-carba-dl-analog exit mainly in a non-chair conformation in solutions, but the latter occupies a chair conformation in a solid state.     

Properties and cage lactone synthesis of diels-alder adducts from 2-pyrones

New cage lactones were synthesized by the photocyclization of the tricyclodienolactones 1a, 1b, 2 which were available from the Diels-Alder reactions of 2-pyrones with p-benzoquinones or norbornadiene. Retro-Diels-Alder reactions of cross-adducts between 2-pyrone-mono-adducts and p-benzoquinone were also described.     

Acetone oxidation using ozone on manganese oxide catalysts

Supported manganese oxide catalysts were prepared by the impregnation of alumina foam blocks washcoated with alumina and silica. The manganese content based on the weight of the washcoats was 10 wt % calculated as MnO2. Fourier transform profiles of the Mn K-edge EXAFS spectra for these samples gave three distinctive peaks at 0.15, 0.25, and 0.32 nm and were close to the profiles of Mn3O4 and beta-MnO2. The number of surface active sites was determined through oxygen chemisorption measurements at a reduction temperature (Tred = 443 K) obtained from temperature-programmed reduction (TPR) experiments. Acetone catalytic oxidation was studied from room temperature to 573 K, and was found to be highly accelerated by the use of ozone on both catalysts with substantial reductions in the reaction temperature. The only carbon-containing product detected was CO2. The alumina-supported catalyst was found to be more active than the silica-supported catalyst in acetone and ozone conversion, with higher turnover frequencies (TOFs) for both reactions. The pressure drop through the foam was low and increased little (0.003 kPa/10 000 h(-1)) with space velocity. In situ steady-state Raman spectroscopy measurements during the acetone catalytic oxidation reaction showed the presence of an adsorbed acetone species with a C-H bond at 2930 cm(-1) and a peroxide species derived from ozone with an O-O bond at 890 cm(-1).     

Modulation of transient stress distributions for controlling femtosecond laser-induced cracks inside a single crystal

After the photoexcitation by a femtosecond laser pulse inside a LiF single crystal, four cracks appear in the <110> directions of the crystal from the photoexcited region. In our previous study, we found that a femtosecond laser-induced stress wave is responsible for generation and elongation of cracks inside a LiF single crystal. This finding suggests that we can control laser-induced cracks by modulating laser-induced stress waves. In this study, we applied parallel fs laser irradiation with a spatial light modulator to generate multiple stress waves at the same time, and found the modulation of crack formation; one crack became thinner and shorter than any other cracks. By a pump-probe imaging of dynamics of crack generation, we showed that the constructive interference of stress waves at a crack tip could compress the crack, which results in a thinner and shorter crack.     

Electrochemical determination of nitrite using a gold nanoparticles-modified glassy carbon electrode prepared by the seed-mediated growth technique.

Seed-mediated growth of gold nanoparticles on glassy carbon (GC) surfaces was developed. The field emission scanning electron microscopy (FE-SEM) and electrochemical characterization confirmed the effective attachment of gold nanoparticles on GC surface with such a wet-chemical method. The as-prepared gold nanoparticles attached glassy carbon electrode (Au/GCE) presented excellent catalytic ability toward the oxidation of nitrite. Compared with bare GCE and planar gold electrode, the Au/GCE obviously decreased the overpotential of nitrite oxidation and improved the peak current. The catalytic current was found to be linearly proportional to the nitrite concentration in the range of 1 x 10(-5) - 5 x 10(-3) M, with a detection limit of 2.4 x 10(-6) M. The Au/GCE was successfully applied to the electrochemical determination of nitrite in a real wastewater sample, showing excellent stability and anti-interference ability.     

Synthesis of polymer microsphere-supported chiral pyrrolidine catalysts by precipitation polymerization and their application to asymmetric Michael addition reactions

Polymer microsphere-supported chiral pyrrolidine catalysts were successfully synthesized by a precipitation polymerization incorporating a methacrylate monomer bearing chiral N-Boc-pyrrolidine moiety, followed by removal of the N-Boc groups. The resulting polymeric catalysts were applied to the asymmetric Michael addition reactions of aldehydes with alkyl vinyl ketones. The effects of the comonomer, the molar ratios within the catalyst, the catalyst loading, the temperature, and the solvent on the catalytic performance were investigated in detail. The reactions were found to proceed smoothly in the absence of a solvent. A hydrophobic polystyrene-based chiral pyrrolidine catalyst exhibited high reactivity (up to 97% yield) and enantioselectivity (up to 95% ee) during these reactions. The catalyst could also be recovered and reused up to five times without significant loss of activity.