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151.
Akano T. Miura Y. Fukatsu K. Miyasaka H. Ikuta Y. Matsumoto H. Hamasaki A. Shioji N. Mizoguchi T. Yagi K. Maeda I. 《Applied biochemistry and biotechnology》1996,57(1):677-688
Applied Biochemistry and Biotechnology - Hydrogen is a clean energy alternative to the fossil fuels, the main source of greenhouse gas emissions. We developed a stable system for the conversion of... 相似文献
152.
153.
Bauxites can be decomposed by condensed phosphoric acid (CPA) very rapidly without the need for subsequent manipulations such as elimination of silica, digestion of fused products and filtration. It is best to heat the samples at about 700 degrees prior to the decomposition, to prevent them from floating on the surface of the CPA. Under the proposed conditions (100 mg of sample, 10 g of CPA, heating at 300 degrees for 30 min), aluminium, iron and titanium are dissolved quantitatively. Iron is determined by photometry with 1,10-phenanthroline after solvent extraction with MIBK, while titanium is determined with N-benzoyl-N-phenylhydroxylamine (BPHA). The effect of phosphate on the determination of titanium is reduced to a minimum at a BPHA concentration of 0.3% and a hydrochloric acid concentration of 7.2M. Aluminium and iron are precipitated quantitatively as the oxinates at pH 5.5 in the presence of orthophosphoric acid or hydrolysed CPA, while the precipitation of titanium oxinate is completely suppressed by the addition of hydrogen peroxide. The total amount of aluminium and iron is obtained by determining the amount of oxine by bromination method. The amount of aluminium is obtained by subtracting the amount of iron from the sum of the two. 相似文献
154.
Mizoguchi H Woodward PM Byeon SH Parise JB 《Journal of the American Chemical Society》2004,126(10):3175-3184
A new polymorph of NaSbO(3) has been synthesized at 10.5 GPa and 1150 degrees C in a uniaxial split sphere anvil type press (USSA-2000) and recovered back to ambient conditions. The high-pressure form of NaSbO(3) adopts an orthorhombically distorted perovskite structure, isostructural with CaTiO(3), GdFeO(3), and NaTaO(3). The space group is Pnma, and the unit cell dimensions are a = 5.43835(6) A, b = 7.66195(8) A, c = 5.38201(5) A. It is a white insulator with an optical band gap of 3.4 eV. This compound represents the first ternary perovskite prepared containing Sb(5+) on the octahedral site. The octahedral tilting distortion in this compound is much larger than expected from ionic radii considerations. The distortion is driven by a second-order Jahn-Teller distortion originating on oxygen that can be traced back to strong Sb-O covalent bonding. A conflict arises between the strong covalent bonding interactions at oxygen that favor a large octahedral tilting distortion and the repulsive Na-O interactions that oppose excessive octahedral tilting. This conflict destabilizes the perovskite topology, thereby stabilizing the ilmenite polymorph under ambient conditions. Analysis of ionic and covalent bonding explains why ASbO(3) and ABiO(3) compositions frequently adopt structures that violate Pauling's rules. 相似文献
155.
Novel methods for the reduction of sulphate to hydrogen sulphide with hypophosphite-tin metal or hypophosphite-iodide in condensed phosphoric acid (CPA) are proposed. The reduction of sulphate with hypophosphite alone does not proceed quantitatively. Sulphate, however, is quantitatively decomposed with hypophosphite when tin metal or potassium iodide is used together with it. The determination of sulphur by the hypophosphite-tin metal-CPA and tin(II)-CPA methods is interfered with by copper on account of the stabilization of copper(I) sulphide, but this interference can be eliminated by adding iodide, e.g. potassium and lead salts. Alum and barytes are quantitatively decomposed within 15 min at 140 and 280 degrees , respectively. The hydrogen sulphide evolved is absorbed in zinc acetate solution at pH 4.5 and then determined by iodometry. 相似文献
156.
The basic study on the determination of tetrafluoroborate ion (BF4−) by ion chromatography, and total boron by conversion of boric acid to BF4− followed by ion chromatography of BF4− has been carried out. The results of thermodynamic calculations for the system of boric acid (H3BO3)-F−-H+ showed that the mole fraction of BF4− was higher than 99% at pH lower than 3.5 and 4.5 when the total free fluoride concentration (2[H2F2] + 2[HF2−] + [HF] + [F−]) was as high as 0.1 and 1.0 M, respectively. The fraction of BF4− increased with increasing total free fluoride concentration. BF4− fraction values were higher than 99% at pH 0.75 and at total free fluoride concentration of 0.05 M or higher. BF4− was hardly formed at pH > 7 even when the total free fluoride concentration was as high as 1.0 M. According to the experimental results, the fraction of BF4− at pH 0.7-0.8 was 51.2, 95.6 and 96.7% when the total fluoride concentration (2[H2F2] + 2[HF2−] + [HF] + [F−] + 3[BF3OH−] + 4[BF4−]) was 0.2, 1.0 and 3.3 M, respectively. The formation reaction of BF4− from boric acid reached an equilibrium state within 20 min regardless of reaction temperature, in the range of 20-50 °C, when the total boron and total fluoride concentrations were 66.7 mM and 1.0 M, respectively. Although BF4− was formed only under acidic conditions, BF4−, once formed, was very stable under alkaline conditions at least for several hours. We have concluded that BF4− could be analyzed by ion chromatography using sodium hydroxide solution as an eluent because BF4− was stable under chromatographic conditions. BF4− solution prepared from boric acid could be used as a standard solution in the ion chromatographic analysis of BF4− instead of the sodium tetrafluoroborate (NaBF4) reagent available commercially, if a discrepancy of about 4-5% was allowed. 相似文献
157.
Treatment of 16 α-amino acid esters with isoamyl nitrite in the presence of a small amount of organic acid in chloroform or benzene, followed by chromatographic purification on alumina was found to afford the corresponding α-substituted-α-diazo esters (1) in fairly good yields. 相似文献
158.
Orita A Hasegawa D Nakano T Otera J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(9):2000-2004
A new method for constructing 5,6,11,12-tetradehydrodibenzo[a,e]cyclooctene is described on the basis of one-pot double elimination protocol. The target molecule, which is the smallest cyclophane with alternate arylene-ethynylene linkage, is synthesized in 61 % yield through oxidative dimerization of ortho-(phenylsulfonylmethyl)benzaldehyde. The initial carbon-carbon bond formation between sp(3) carbons followed by stepwise conversion to sp(2) and finally sp carbons bypasses the difficulty encountered in direct coupling of the sp carbon in the terminal acetylene. The mechanism of this process is discussed. The Wittig-Horner-type coupling is a key reaction employed for the carbon-carbon bond formation. Generation of (E)-vinylsulfone moiety in the first coupling between alpha-sulfonyl anion and aldehyde functions is crucial for the effective second coupling to complete the cyclization. The syn-elimination of the (E)-vinylsulfone moieties in the cyclized intermediate furnishes the acetylenic bonds. 相似文献
159.
Sigeru Torii Hideo Tanaka Michio Sasaoka Norio Saitoh Takashi Siroi Junzo Nokami 《Tetrahedron letters》1982,23(24):2495-2498
Direct transformation of thiazoline-azetidinones , derived from penicillin G and V, into 3′-thio-substituted cephalosporins has been performed by ring opening of the thiazoline moiety with sulfenyl chlorides followed by ring closure with NH3 in dimethylformamide and simultaneous displacement of the allylic chlorine atom with the leaving thiolates. 相似文献
160.
Umeda Fusako Yano Kazuhiro Gohda Noritsugu Fujihara Kikuno Maeda Isamu Yagi Kiyohito Miura Yoshiharu Mizoguchi Tadashi 《Applied biochemistry and biotechnology》1996,57(1):367-373
Applied Biochemistry and Biotechnology - Pseudomonas oxalaticus OX1 carrying recombinant plasmid pFUS and 29 gramnegative bacteria were used as donor and recipients, respectively, for conjugations.... 相似文献