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991.
A palladium-catalyzed CO(2)-recycling reaction has been developed. Reaction of 4-methoxycarbonyloxy-2-butyn-1-ols with phenols, carried out in the presence of a palladium catalyst, produces phenoxy-substituted cyclic carbonates by way of a pathway involving a CO(2) elimination-fixation. A variety of propargylic alcohols and phenols participate in these reactions which yield cyclic carbonates with high efficiencies. Stereoselective construction of trans-cyclic carbonates is achieved by using nonsymmetric substrates. Highly enantioselective reactions occur when (S)-BINAP is used as a ligand. Reaction of 4-phenoxycarbonyloxy-2-butyn-1-ol in the presence of the palladium catalyst yields the corresponding cyclic carbonates via a three-component decomposition-reconstruction process. 相似文献
992.
Kunio Miki Masahiro Yama Yasushi Kai Nobutami Kasai 《Journal of organometallic chemistry》1982,239(2):417-428
The molecular structure of a three-coordinate palladium(II)-styrene complex, [Pd(η5-C5H5)(PEt3)(styrene)]BF4 has been determined by means of X-ray diffraction. The crystal belongs to the monoclinic system, space group P21/c, with four formula units in a cell of dimensions: a 10.229(3), b 11.262(3), c 18.760(5) Å and β 103.77(2)°. The structure was solved by the heavy atom method, and refined by the least-squares procedure to R = 0.050 for 3635 observed reflections. The palladium atom is surrounded by the cyclopentadienyl group, the triethylphosphine ligand and the olefinic bond of styrene in the cationic complex. In the palladiumstyrene bonding, the olefinic bond is inclined by 77.3° to the coordination plane defined by the Pd and P atoms and the center of the cyclopentadienyl ring (PdC(1) 2.176(6), PdC(2) 2.234(5) and C(1)C(2) 1.369(8) Å). 相似文献
993.
We have applied cavity ring-down spectroscopy to a kinetic study of the reaction of NO3 with CH3I in 20-200 Torr of N2 diluent at 298 K. The rate constant of the reaction of NO3 + CH3I was determined to be (4.1 +/- 0.2) x 10(-13) cm3 molecule(-1) s(-1) in 100 Torr of N2 diluent at 298 K and is pressure-independent. This reaction may significantly contribute to the formation of reactive iodine compounds in the atmosphere. 相似文献
994.
Yasuhiro Fuma Masahiro Ebihara 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(7):m284-m289
In diaquatetra‐μ‐acetamidato‐κ4N:O;κ4O:N‐dirhodium(II,III) hexafluorophosphate, [Rh2(C2H4NO)4(H2O)2]PF6, and diaquatetra‐μ‐acetamidato‐κ4N:O;κ4O:N‐dirhodium(II,III)hexafluorophosphate dihydrate, [Rh2(C2H4NO)4(H2O)2]PF6·2H2O, the cations and anions lie on inversion centers. Diaquatetra‐μ‐propionamidato‐κ4N:O;κ4O:N‐dirhodium(II,III) hexafluorophosphate dihydrate, [Rh2(C3H6NO)4(H2O)2]PF6·2H2O, and diaquatetra‐μ‐butyramidato‐κ4N:O;κ4O:N‐dirhodium(II,III) hexafluorophosphate, [Rh2(C4H8NO)4(H2O)2]PF6, crystallize with two crystallographically independent complexes that lie on inversion centers. In all of the structures, the dirhodium units are hydrogen bonded to one another. The hydrogen‐bonded networks vary with the alkyl substituents. 相似文献
995.
Nakamura T Suzuki M Ishihara M Ohana T Tanaka A Koga Y 《Langmuir : the ACS journal of surfaces and colloids》2004,20(14):5846-5849
Photolysis of perfluoroazooctane with diamond films led the chemical modification of the surface to introduce perfluorooctyl functional groups, confirmed by means of Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and time-of-flight secondary ion mass spectrometry measurements. Diamond films modified with fluorine moieties showed improved frictional property and reduction of surface energy, as evaluated by contact angle to water, compared with a pristine diamond film. The contact angle and friction coefficient of chemically modified diamond film are 118 degrees and 0.1, respectively. The results of the value of the contact angle depending on irradiation times are consistent with those of the F/C ratio of fluorinated diamond films by monitoring with XPS. 相似文献
996.
Nobuyuki Tanaka Chie Okabe Kenji Sakota Tuyoshi Fukaminato Tsuyoshi Kawai Masahiro Irie Alexander Goldberg Shinichirou Nakamura Hiroshi Sekiya 《Journal of Molecular Structure》2002,616(1-3):113-118
The fluorescence excitation and dispersed fluorescence spectra of the open-ring isomer of 1,2-bis(3-methyl-2-thienyl)perfluorocyclopentene have been measured in a supersonic free jet. No vibronic structure has been observed in the excitation spectrum. The intensity of fluorescence gradually increases with the excitation energy in the 25,500–28,700 cm−1 region, indicating that the geometry of the molecule substantially changes upon photoexcitation. The dispersed fluorescence spectrum is anomaly Stokes-shifted with respect to the excitation energy, suggesting that the S2(1B) state is initially excited followed by rapid internal conversion from the S2(1B) to S1(2A) state. The fluorescence is due to the S1(2A)–S0(1A) transition. Density functional theory calculations at the B3LYP/6-31G** level have been carried out to investigate stable conformations responsible for the observed spectra. 相似文献
997.
Kazuhisa Murata Megumu Inaba Masahiro Saito Isao Takahara Naoki Mimura 《Reaction Kinetics and Catalysis Letters》2003,80(1):39-44
The stability of an Fe/Al2O3 catalyst in the methane decomposition in the presence of O2/CO2 was found to be improved by the addition of Mg into the catalyst (Mg/Fe=1/1 wt ratio), probably due to suppression of carbon
deposition even under CH4/ O2/CO2 (80/10/5 vol. ratio) conditions.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
998.
A novel alkenylation reaction of pyridine is developed. Heating a cationic ruthenium vinylidene complex [CpRu(=C=CHR)(PPh(3))(2)]PF(6) in pyridine at 100-125 degrees C for 24 h affords (E)-2-alkenylpyridine. Initially, pyridine coordinates to ruthenium by displacement of one of the phosphine ligands. Then, [2 + 2] heterocycloaddition occurs to form a four-membered ruthenacyclic complex. Deprotonation of the beta-hydrogen affords a neutral pi-azaallyl complex. Protonolysis furnishes the product. As a result, a vinylidene group is inserted into the alpha C-H bond of pyridine. The alkenylation reaction is made catalytic in ruthenium by the use of (alkyn-1-yl)silane as the vinylidene source. Treatment of (alkyn-1-yl)trimethylsilane with pyridine in the presence of a cationic ruthenium complex [CpRu(PPh(3))(2)]PF(6) affords the corresponding (E)-2-alkenylpyridine in good yield in a regio- and stereoselective manner. 相似文献
999.
A newly designed anthryl dendron having perfluoroalkyl chains at terminals showed thermotropic liquid crystallinity, which was characterized using polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction. The anthryl dendron forms SB phase at room temperature below 53 °C, at which temperature a phase transition to Colrd takes place. In a fluorous solvent, regioselective photodimerization of the anthryl dendron occurred to give head-to-head photodimers, although photodimerization in the SB phase and chloroform gave both head-to-head and head-to-tail photodimers. 相似文献
1000.
Masayuki Kitamura Noritaka Usami Takamasa Sugawara Kenrato Kutsukake Kozo Fujiwara Yoshitaro Nose Toetsu Shishido Kazuo Nakajima 《Journal of Crystal Growth》2005,280(3-4):419-424
The floating zone technique was employed to grow multicrystalline Si with controlled grain boundary configuration. Purposely designed bi-crystals were utilized as seed crystals to investigate the effect of the tilt angle from the perfect twin boundary on the growth behavior. When the growth was initiated from a bi-crystal with a Σ3 twin boundary, no particular change took place on the grain boundary configuration during growth. On the other hand, the decrease of the tilt angle during growth was observed when the growth was initiated from a bi-crystal with a tilted boundary from Σ3. This was accompanied by the appearance of new crystal grains. The reduction of the total interface energy would be a possible driving mechanism for this phenomenon. 相似文献