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11.
T. Ishihara K. Nishida H. Nishiguchi Y. Takita K. Chaki 《Research on Chemical Intermediates》2006,32(3-4):253-262
A new reforming process was studied using Ni/SiO2 with a hydrogen-permeating membrane reactor. Nickel catalyst supported on SiO2 is highly active for CH4?H2O?O2 reaction in membrane reactor and the reaction close to CH4+0.35O2+1.3H2O→CO2+3.3H2 proceeds at 873 K. Since the selectivity to carbon and CO2 increased and decreased with decreasing contact time respectively, it is considered that the reaction was started by decomposition of CH4 followed by oxidation of C and water shift reaction. Therefore, the reaction mechanism was different from so-called autothermal reforming (ATR) reaction. 相似文献
12.
Homogeneous solutions are formed from equimolar amounts of Ce(NH4)2(NO3)6 and EDTA. These solutions hydrolyze single-stranded DNA far more efficiently than double-stranded DNA. In contrast, Ce(IV) hydroxide gel, obtained in the absence of EDTA, hydrolyzes both single-stranded and double-stranded DNAs at almost the same rates. In order to achieve this substrate-specificity sufficiently, the mole ratio of EDTA to Ce(NH4)2(NO3)6 must be 1.0 or greater. By using this remarkable specificity of Ce(IV)/EDTA complex, gap-site in substrate DNA is selectively hydrolyzed. The scission-site is modulated by use of appropriate combination of oligonucleotide additives. The reactions have been kinetically analyzed. 相似文献
13.
Tsutomu Konno Jungha Chae Tomoo Tanaka Takashi Ishihara Hiroki Yamanaka 《Journal of fluorine chemistry》2006,127(1):36-43
Hydroalumination, hydrocupration, and hydroboration reactions of various fluorine-containing alkynes were investigated. The alkyne reacted smoothly with 2.0 equiv. of Red-Al at −78 °C to give the hydroaluminated adduct in a highly regio- and stereoselective manner, which was treated with iodine, the corresponding vinyliodide being produced in moderate yield. Hydrocupration of the alkynes also took place, but the resulting vinylmetal reacted with various electrophiles sluggishly. In sharp contrast, the reaction with dicyclohexylborane proceeded smoothly to afford the cis-addition products preferentially, which were subjected to Suzuki-Miyaura cross-coupling reaction, leading to trisubstituted alkenes in high yields. 相似文献
14.
The mass resolution of a time-of-flight (TOF) mass spectrometer is directly proportional to its total flight pathlength. Multi-turn or multi-passage ion optical geometries are necessary to obtain fight distances of sufficient length within reasonable size limitations. We have investigated ion optics for a multi-turn TOF mass spectrometer with electrostatic sectors. The concept of 'perfect' focusing conditions is introduced. Furthermore, a new type of multi-turn TOF mass spectrometer, the MULTUM Linear plus, was developed. It consists of four cylindrical electric sectors and 28 electric quadrupole lenses. It has a vacuum chamber 60 x 70 x 20 cm in size. Mass resolution is demonstrated to increase according to the number of ion cycles. A mass resolution of 350 000 (m/z = 28, FWHM) was achieved after 501.5 cycles. The MULTUM Linear plus analyzer is not simple, however; 28 electric quadrupole lenses are used. In order to reduce the number of ion optical parts, an improved multi-turn TOF mass spectrometer, the MULTUM II, consisting of only four toroidal electric sectors, was also developed. The possibility of tandem mass spectrometric applications using multi-turn TOF mass spectrometers is also discussed. 相似文献
15.
Inhibition of acetylcholinesterase (AChE) activity by essential oils of Citrus paradisi (grapefruit pink in USA) was studied. Inhibition of AChE was measured by the colorimetric method. Nootkatone and auraptene were isolated from C. paradisi oil and showed 17-24% inhibition of AChE activity at the concentration of 1.62 microg/mL. 相似文献
16.
A new strategy using a BINOL derivative as a chiral leaving group and Lewis acid has been developed for enantioselective alkylation of prochiral olefins. (R)-2,2'-Bis[2-(trimethylsilyl)ethoxymethyl]-1,1'-binaphthol is demonstrated to be an effective reagent for enantioselective hydroxymethylation of silyl enol ethers and trisubstituted alkenes. Electrophilic addition to prochiral olefins is accompanied by cleavage of an acetal that is dual activated by SnCl4 and the delta-effect of silicon through the S(N)2 substitution process. Enantioselective synthesis of cyclic terpenes is also described using this strategy. 相似文献
17.
Zhang X Furutachi H Fujinami S Nagatomo S Maeda Y Watanabe Y Kitagawa T Suzuki M 《Journal of the American Chemical Society》2005,127(3):826-827
(mu-Hydroxo or oxo)(mu-1,2-peroxo)diiron(III) complexes having a tetradentate tripodal ligand (L) containing a carboxylate sidearm [Fe2(mu-OH or mu-O)(mu-O2)(L)2]n+ were synthesized as models for peroxo-intermediates of non-heme diiron proteins and characterized by various physicochemical measurements including X-ray analysis, which provide fundamental structural and spectroscopic insights into the peroxodiiron(III) complexes. 相似文献
18.
Herold S Kalinga S Matsui T Watanabe Y 《Journal of the American Chemical Society》2004,126(22):6945-6955
Hemoproteins are known to react with the strong nitrating and oxidizing agent peroxynitrite according to different mechanisms. In this article, we show that the iron(iii) forms of the sperm whale myoglobin (sw Mb) mutants H64A, H64D, H64L, F43W/H64L, and H64Y/H93G catalyze the isomerization of peroxynitrite to nitrate. The two most efficient catalysts are H64A (k(cat) = (5.8 +/- 0.1) x 10(6) M(-1) s(-1), at pH 7.5 and 20 degrees C) and H64D metMb (k(cat) = (4.8 +/- 0.1) x 10(6) M(-1) s(-1), at pH 7.5 and 20 degrees C). The pH dependence of the values of k(cat) shows that HOONO is the species which reacts with the heme. In the presence of physiologically relevant concentrations of CO(2) (1.2 mM), the decay of peroxynitrite is accelerated by these metMb mutants via the concurring reaction of HOONO with their iron(iii) centers. Studies in the presence of free added tyrosine show that the metMb mutants prevent peroxynitrite-mediated nitration. The efficiency of the different sw metMb mutants correlates with the value of k(cat). Finally, we show that sw WT-metMb is nitrated to a larger extent than horse heart metMb, a result that suggests that the additional Tyr151 is a site of preferential nitration. Again, the extent of nitration of the tyrosine residues of the metMb mutants correlates with the values of k(cat). 相似文献
19.
Mantani T Shiomi K Konno T Ishihara T Yamanaka H 《The Journal of organic chemistry》2001,66(10):3442-3448
N,N-Dialkyl(3,3,3-trifluoro-1-propynyl)amines were readily prepared by a three-step procedure starting from commercially available 2,2,3,3,3-pentafluoropropanol. These fluorinated alkynylamines reacted smoothly with a variety of aldehydes or ketones in the presence of a catalytic amount of Lewis acid and molecular sieves 4A at ambient temperature to produce the corresponding alpha-(trifluoromethyl)-alpha,beta-unsaturated amides in good to excellent yields with high Z-stereoselectivity. 相似文献
20.
Balakin V Alexandrov VA Mikhailichenko A Flöttmann K Peters F Voss G Bharadwaj V Halling M Holt JA Buon J Jeanjean J LeDiberder F Lepeltier V Puzo P Heimlinger G Settles R Stierlin U Hayano H Ishihara N Nakayama H Oide K Shintake T Takeuchi Y Yamamoto N Bulos F Burke D Field R Hartman S Helm R Irwin J Iverson R Rokni S Roy G Spence W Tenenbaum P Wagner SR Walz D Williams S 《Physical review letters》1995,74(13):2479-2482