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991.
K. Suzuki M. Takahashi M. Takeda T. Kitazawa 《Journal of Radioanalytical and Nuclear Chemistry》2003,255(2):305-309
Four kinds of Dy(III) hexacyanometalates (II or III), DyFe(CN)6·4H2O (1), KDyFe(CN)6·4H2O (2), DyCo(CN)6·4H2O (3), and KDyRu(CN)6·4H2O (4) have been investigated by 161Dy Mössbauer spectroscopy. 161Dy isomer shifts of four compounds fall in the range of +3 ionic compounds. Although all spectra 1-4 show an almost symmetric line, the broadening of the line-width is observed on lowering the temperature due to the paramagnetic relaxation. As a parameter of intermolecular force constant, the M2 value obtained for 161Dy of 1 is slightly larger than that of 2. 相似文献
992.
993.
Takayuki Ban Yutaka Ohya Yasutaka Takahashi 《Journal of Sol-Gel Science and Technology》2003,27(3):363-372
A clear alcoholic solution of titanium alkoxide with an addition of various alkanolamines is suitable for a sol-gel coating of titania films. The reaction of titanium isopropoxide, Ti(OPr
i
)4 (TIP), with alkanolamines, such as triethanolamine (TEAH3), diethanolamine (DEAH2), and N-ethyldiethanolamine (EDEAH2), and an association of the Ti species in the resultant mixtures were examined via liquid-state nuclear magnetic resonance (NMR), infrared spectroscopy (IR), and cryoscopy measurements. Regardless of the kinds of the alkanolamines used, the IR and NMR spectra showed that alcohol exchange reactions occurred between the alcoholic moieties in alkanolamines and the isopropoxy groups in TIP, and that the N atom in the alkanolamines might be datively bonded to Ti. In the DEAH2 and EDEAH2 systems with the molar ratio of amine/TIP = 1, the results of the NMR and cryoscopy measurements showed that an association degree of the formed Ti species increased with an increase in the concentration of TIP, according to the thermodynamical equilibriums of associations between various oligomers. The increase was larger in the DEAH2 system than in the EDEAH2 one, because of the larger equilibrium constants due to the smaller size of the DEA group. In the system of EDEAH2/TIP = 2, the NMR spectra showed that only one kind of oligomer was formed as a Ti species, independent of the concentration of TIP. The oligomer may be a much more stable species than other species. The cryoscopy results showed that the oligomer had a tetrameric structure. 相似文献
994.
Takahashi K Kawakami T Gu ZZ Einaga Y Fujishima A Sato O 《Chemical communications (Cambridge, England)》2003,(18):2374-2375
The first preparation of an Fe(II) spin-crossover complex including a 1,3-dithiole ligand is reported. Crystal analyses of both the low- and the high-temperature phases reveal that short S...S contacts play a key role in an abrupt spin transition. 相似文献
995.
Takahashi S Souma K Hashimoto R Koshino H Nakata T 《The Journal of organic chemistry》2004,69(13):4509-4515
The C(2)-symmetric macrodiolide core 2 of an antiviral agent, macroviracin A (1), was constructed in a single step by the intermolecular macrodimerization of C(22)-hydroxy carboxylic acid 3 with 2-chloro-1,3-dimethylimidazolinium chloride and DMAP in the presence of sodium hydride (NaH). The use of potassium hydride instead of NaH caused the intramolecular cyclization, predominantly providing the corresponding monomer 26. The acid 3 was synthesized through a series of reactions such as the coupling reaction of acetylene 5 and oxirane 6, stereoselective glycosidation with the trichloroacetimidate method, and Jones oxidation. 相似文献
996.
Iwase Y Takahashi M Takemura Y Ju-ichi M Ito C Furukawa H Yano M 《Chemical & pharmaceutical bulletin》2001,49(10):1356-1358
Two new flavanones and one chalcone were isolated from the peel of Citrus kinokuni Hort. ex Tanaka and identified as (2S)-5,6,7,8,4'-pentamethoxyflavanone (1), (2S)-5,6,7,3',4'-pentamethoxyflavanone (2) and 2'-hydroxy-3,4,3',4',6'-pentamethoxychalcone (3). The structures of new compounds were elucidated by spectroscopic analysis. 相似文献
997.
Shuntaro Mataka Kazufumi Takahashi Masashi Tashiro 《Journal of heterocyclic chemistry》1977,14(6):963-964
The reaction of tetrasulfur tetranitride with alkoxybenzenes such as anisole ( 1a ), o- ( 1b ), m-( 1c ), p-dimethoxybenzenes ( 1d ), and benzyl ether ( 1e ) was investigated. Benzo[1,2-c:3,4-c′ :5,6-c ]-tris[1,2,5]thiadiazole ( 2 ) and benzo[1,2, c:3,4-c′ ]bis[1,2,5]thiadiazoles ( 3a and 3b ) were isolated. J. Chem. Soc., 14, 963 (1977) 相似文献
998.
A new synthetic method of (+)-(1R)-acetyl-(7aR)-methyl-4-hydroinden-5-one (2) by highly enantioselective double Michael addition involving alkenylcopper-phosphine complex, 3-trimethylsilylbutenone and 2-methyl-2-cyclo-pentenone is presented. 相似文献
999.
Tamotsu Takahashi Masanori Ishikawa Shoquan Huo 《Journal of the American Chemical Society》2002,124(3):388-389
Reactions of zirconacyclopentadienes with dichlorocarbene afforded cyclopropanation products in good yields. In a similar manner, reactions of zirconacyclopentadienes with a Simmons-Smith type cyclopropanation reagent also gave vinylcyclopropanes in good yields after hydrolysis. Before hydrolysis, the formation of 1-zirconabicyclo[3.1.0]hexene was observed by 13C NMR spectroscopy. The 1-zirconabicyclo[3.1.0]hexene deriatives reacted with CO to produce 1,2,3,5-tetrasubstituted benzene derivatives in good yields via the C-C bond cleavage of the cyclopropane rings. This is in sharp contrast to the formation of usual 1,2,3,4-tetrasubstituted benzene derivatives from zirconacyclopentadienes. 相似文献
1000.
Yoshio Imai Takeyoshi Takahashi Mitsuru Ueda 《Journal of polymer science. Part A, Polymer chemistry》1982,20(6):1497-1503
New polymer-forming monomers, 3-benzylidene-5-chloroformylphthalide and 3-benzylidene-6-chloroformylphthalide, were synthesized by the Perkin reaction of trimellitic anhydride with phenylacetic acid, followed by chlorination. The polycondensation of these monomers with aromatic diamines in N-methyl-2-pyrrolidone at 200°C afforded aromatic polyamide-phthalimidines having inherent viscosities of 0.2-0.5 dL/g. All the polymers were readily soluble in m-cresol, pyridine, dimethylformamide, and dimethyl sulfoxide. Glass transition temperatures of some of the polymers were in the range of 255–282°C. The polyamide-phthalimidines began to lose weight at around 300°C in both air and nitrogen atmospheres, with 10% weight losses being recorded at 435–475°C in nitrogen by thermogravimetry. 相似文献