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21.
Takakazu Yamamoto Junichi Ishizu Sanshiro Komiya Yoshiyuki Nakamura Akio Yamamoto 《Journal of organometallic chemistry》1979,171(1):103-112
13C NMR data are given for a series of phosphinenickel(0) complexes of ethyl methacrylate (ema), Ni(PR3)2(CH2=C(CH3)COOC2H5) (PR3 = PPh3 (Ia), PEtPh2 (Ib), PEt2Ph (Ic), PMe2Ph (Id), PEt3 (Ie)). The olefinic carbon signals of ema shift upfield by 71.5–86.5 ppm on coordination, the magnitude of the upfield shift increasing with increase in the bacisity of the phosphine ligand. The effect of the basicity of PR3 is discussed on the basis of the back-bonding from Ni to ema. Variable temperature1H NMR studies reveal that the ema of Id, the complex having the least sterically demanding phosphine ligands, exchanges with free ema in toluene on the NMR time scale. The dependence of the rate of exchange on the concentration of ema shows that the exchange proceeds through anSN2 mechanism. The activation parameters are: ΔH273≠ 2.75 kcal/mol, ΔG273≠ 12.7 kcal/mol, ΔS273≠ ?37 e.u. The31P NMR spectra of the complexes show two doublets when the exchange is frozen out, indicating the inequivalence of the two phosphine ligands in the ema-coordinated complex. The difference in the31P chemical shifts of the two coordinated tertiary phosphines increases with increase in the basicity of the PR3 ligand. 相似文献
22.
Oludotun A. Phillips Eduardo L. Setti Andhe V. N. Reddy Ronald G. Micetich Chieko Kunugita Akio Hyodo Samarendra N. Maiti 《Chemistry of Heterocyclic Compounds》1998,34(11):1319-1323
Two monobactam derivatives, potassium 4-methyl-(3E)-[(thien-2-yl)methylene]-2-azetidinone-1-sulfonate and its (3Z)-isomer, were prepared and evaluated for their -lactamase inhibitory activities. These compounds were devoid of -lactamase inhibitory activity.SynPhar Laboratories Inc., #2, 4290-91A Street, Edmonton, Alberta T6E 5V2, Canada. Tokushima Research Institute, Taiho Pharmaceutical Co., Ltd., 224-2 Ebisuno Hiraishi, Kawauchi-cho, Tokushima 771-01, Japan. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1548–1552, November, 1998. 相似文献
23.
Kazunori Maruyama Takashi Ito Akio Yamamoto 《Journal of organometallic chemistry》1978,157(4):463-474
Carbon monoxide is readily inserted into the phenyl—nickel bond of PhNi(acac)(PR3)n to give benzoylnickel complexes, PhCONi(acac)PR3 (R = Ph, Et, cyclo-C6H11), which were characterized by elemental analysis, IR and NMR spectroscopy, as well as chemical reactions. The reactions of the benzoylnickel complexes with methyl iodide and alcohols give acetophenone and corresponding benzoates, respectively, accompanied by some decomposition reactions. The solid benzoylnickel complexes when heated at elevated temperatures are decarbonylated and biphenyl, benzophenone and carbon monoxide are liberated. The dynamic behavior of the acac ligand in acetone solution was studied and the activation parameters for the acac exchange reactions were obtained. The decarbonylation reaction of the benzoyl complex PhCONi(acac)PPh3 in acetone was studied by NMR, and found to be first order in the benzoylnickel complex. 相似文献
24.
The simultaneous ultramicrodetermination of heterogeneous halogens in organic compounds was carried out by the potentiometric titration with 0.002 M silver nitrate after the sample was decomposed by the flask combustion method. In examination of the titration, it was found that clear potential break at the end point was obtained by controlling the delivery speed of the titrant at 0.2 ml/min or slower and the temperature of the solution to be titrated at ca. 10 °C when chloride ion is present. The error due to coprecipitation during the titration and the effect of the mole ratio of heterogeneous halide ions in the sample solution was examined and discussed. The analysis of organic halogen compounds resulted in an error of within 0.4% and standard deviation of less than 0.25%. 相似文献
25.
Masao Tokuda Yasufumi Yamada Toshiya Takagi Hiroshi Suginome Akio Furusaki 《Tetrahedron letters》1985,26(49):6085-6088
Neutral aminyl radicals generated by anodic oxidation of lithium alkenylamides 2 undergo a stereoselective cyclization to give -1-methyl-2,5-disubstituted pyrrolidines 4. Their stereochemistry was confirmed by a comparison with -1,2-dimethyl-5-phenylpyrrolidine, the structure of which was established by X-ray crystallographic analysis of its quarternary ammonium bromide 6. 相似文献
26.
New low-molecular-weight gelators based on l-valine and l-isoleucine gelators, which have a positively charged terminal group, can gel not only pure water and aqueous solutions containing inorganic acids and salts but also some organic solvents and oils. 相似文献
27.
Akio Saito 《Tetrahedron letters》2007,48(5):835-839
Perfluorooctanesulfonic acid (PFOSA), Brønsted acid-surfactant-combined catalyst, efficiently catalyzes the Pictet-Spengler reactions of β-arylethyl carbamate derivatives with aldehydes in water. The present reaction is accelerated by the addition of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). 相似文献
28.
Koichi Shiomi Masao Shimono Hiromi Arimoto Seiji Takahashi 《Journal of separation science》1991,14(11):729-737
A slightly modified, commercially available high resolution capillary gas chromatograph and a PC-based data processing system running proprietary software (“PONA”) have been employed in the development of a system for petroleum type analysis which would be equivalent or superior to the FIA (fluorescent indicator adsorption) method in terms of ease of use and the speed, variety, and accuracy of the analytical data produced. The system is capable of performing identification and quantitation of most of the individual components in a complex gasoline sample consisting of more than 230 components and can report weight percentage and/or volume percentage for each component as well as types by carbon number (e.g., isoparaffins, normal paraffins, olefins, naphthenes, aromatic compounds) within a ca. 70 minute analysis cycle. Precolumn sulfonation to trap olefins and aromatic compounds has been used as an complementary technique to the basic mass spectrometric identification of components of interest. The estimation of correction factors for weight percentage (or volume percentage) calculation are also discussed. Comparisons are made between this system and others, and the results indicate that the proposed method supersedes the conventional method employing FIA. 相似文献
29.
Adsorption of anions to zirconium(IV) and titanium(IV) chemically immobilized on gel-phase 总被引:1,自引:0,他引:1
Adsorption behaviors of 25 anions to zirconium(IV) and titanium(IV) chemically immobilized on a gel-phase were studied by ion chromatography and by batch adsorption experiments. The affinities of Zr(IV) to iminodiacetate as an anchoring group and to anions as a sample are much stronger than those of Ti(IV). On a Zr(IV) column, fourteen anions showed no retention, four anions showed pH-dependent retention in a low pH region, and seven anions were irreversibly adsorbed at pH <7. In the last group, fluoride was adsorbed both by the ligand exchange mechanism and the addition mechanism, while phosphate, arsenate and selenite were only by the ligand exchange mechanism. The structures of the adsorbed species are discussed. 相似文献
30.
The density functional theory was employed to investigate Eu(III) complexes with three beta-diketonates and two phosphine oxides (complex M1: Eu(bdk)3(TPPO)2, complex M2: Eu(bdk)3(TMPO)2, and complex M3: Eu(bdk)3(TPPO)(TMPO)) deemed to be the model complexes of the fluorescence compounds for the ultraviolet LED devices we have recently developed. For each complex, two minimum energy points corresponding to two different optimized geometries (structures A and B) have been found, and the difference of the energy between two minimum energy points is found to be quite small (less than 1 kcal/mol). Vertical excitation energies and oscillator strengths for each complex at two optimized geometries have been obtained by the time-dependent density functional theory, and the character of the excited states has been investigated. For complex M3, the absorption edge is red-shifted, and the oscillator strengths are relatively large. The efficiency of intersystem crossing and energy transfer from the triplet excited state to the Eu(III) ion is considered by calculating DeltaE(ISC) (the energy difference between the first singlet excited state and the first triplet excited state) and DeltaE(ET) (the difference between the excitation energy of the complex for the first triplet excited state and the emission energy of the Eu(III) ion for 5D to 7F). 相似文献