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41.
Kinetic experiments have been carried out on the reactions of isoquinoline N-oxide with p-toluenesulfonyl and other substituted benzenesulfonyl chlorides, varying solvent and salt compositions. The rate was correlated by the second-order equation, i.e., v = [N → O] × [ArSO2Cl], and was found to be accelerated in polar media. The addition of chloride ion was found to increase the rate considerably, while the rates of the over-all reaction became greater with arenesulfonyl chlorides bearing stronger electron-withdrawing substituents ( = +2·0). By the use of 1-deuterated isoquinoline N-oxide a small kinetic isotope effect (kH/kD = 1·2) was observed for this reaction. Based on these kinetic observations the rate-determining step of this reaction is considered to be the cleavage of N---O bond. Meanwhile, from the 18O-tracer experiments in several solvents using uniformly 18O-labelled p-toluenesulfonyl or p-bromobenzenesulfonyl chloride the migration of arenesulfonate was found to proceed mainly via oxygen-bridged ion pair pathway. 相似文献
42.
Treatment of Mn(CO)5SiTolp2H (2) with an excess of LiAlH4, NaBH4, or NaBH3(CN) in THF at room temperature gave hydrosilane H---SiTolp2H in high yield together with Mn2(CO)10. No reduction of CO ligands was observed. On the other hand, treatment of 2 with an excess of Red-Al (=Na[(CH3OCH2CH2O)2AlH2]) in toluene and subsequent addition of aqueous acidic solution afforded alkylsilanols (CH3)SiTolp2(OH) and (C2H5)SiTolp2(OH). Treatment of the reaction mixture of 2 and Red-Al with LiAlH4 in diethyl ether instead of hydrolysis gave alkylhydrosilanes (CH3)SiTolp2H and (C2H5)SiTolp2H. The methyl and ethyl groups on silicon originate from the CO ligands in 2. These products clearly demonstrate that not only the Si---C coupling, but also C---C coupling occurs efficiently in this reaction. 相似文献
43.
Yamamoto A Nakamura K Furukawa K Konishi Y Ogino T Higashiura K Yago H Okamoto K Otsuka M 《Chemical & pharmaceutical bulletin》2002,50(1):47-52
To find new tachykinin NK1 receptor antagonists from natural sources, we examined the tachykinin antagonist activity in the extracts of approximately 200 species of plants by the use of isolated guinea pig ileum. As a result, we discovered a novel and potent NK1 receptor antagonist in the extract of dried flowers of Matricaria chamomilla L. (chamomile). The structure of the antagonist was established as N1,N5,N10,N14-tetrakis[3-(4-hydroxyphenyl)-2-propenoyl]-1,5,10,14-tetraazatetradecane (tetracoumaroyl spermine, 1a). The Ki values of 1a, estimated from the inhibitory action on the substance P (SP)-induced contraction of the guinea pig ileum and the inhibition of the binding of [3H][Sar9, Met(O2)11]SP to human NK1 receptors, were 21.9 nM and 3.3 nM, respectively. 1a is the first potent NK1 receptor antagonist from natural sources and it has a unique structure of a polyacylated spermine. 1a was concentrated in pollen of Matricaria chamomilla L. and was also found in the extracts of flowers of other four species of Compositae. In addition, we found N1,N5,N10-tris[3-(4-hydroxyphenyl)-2-propenoyl]-1,5,10,14-tetraazatetradecane (2) as a new compound in the extract of flowers of Matricaria chamomilla L., which did not exhibit any tachykinin antagonist activity. A number of related compounds were synthesized, and the structure-activity relationship was studied. 相似文献
44.
45.
We report on the photophysical characterization at the single-molecule level of a graft copolymer consisting of a polythiophene backbone and long polystyrene branches. The presence of the branches prevents the polymer chain from forming a collapsed conformational state. The photophysical properties of the resulting solution-like conformation are studied by measuring single-molecule photobleaching dynamics, emission polarization anisotropy and emission spectra. The results are compared with those obtained on the same polythiophene derivative without the branches. It is found that the presence of the branches is a decisive factor in determining the photophysical properties of the polymers on the single-molecule level. 相似文献
46.
NHC-coordinated cyclometalated palladium(II) catalyzed addition of arylboronic acids to methyl 2-hydroxy-2-methoxyacetate gave corresponding various functionalized methyl mandelate derivatives in good yields. 相似文献
47.
Polystyrene (PSt)/poly (4-butyltriphenylamine; PBTPA) composite particles was prepared by a chemical oxidative seeded dispersion
polymerization of (4-butyltriphenylamine) with PSt seed particles that were prepared by nonaqueous dispersion polymerization
of styrene. Monodisperse composite particles were obtained when the ratio of monomer to seed, the rate of monomer feed, and
poly(N-vinyl pyrrolidone; PVP) concentration was appropriately selected. The introduction of PBTPA was confirmed by the presence
of the characteristic absorption band attributed to PBTPA from a Fourier transform infrared spectra. The solvent extraction
with ethyl acetate revealed that composite particles consisted of PSt core and PBTPA shell. Then two-dimensional arrays of
composite particles were also fabricated. 相似文献
48.
A series of semiconducting and symmetrical 2,9-dialkylpentacenes was successfully synthesized via a five-step process and their structures confirmed by 1H NMR, IR and elemental analyses. Their liquid crystallinity was investigated by differential scanning calorimetry and polarizing optical microscopy. The introduction of alkyl chains also improved their solubility. For alkyl chains longer than butyl, focal conic or baton texture was observed, indicating the existence of an ordered smectic phase. Thermal analyses revealed that the both melting and smectic-isotropic transition temperatures show an odd-even effect when the alkyl chain is larger than heptyl or octyl. The synthesized compounds are promising candidates for semiconductors in organic field-effect transistors because their liquid crystallinity allows easy molecular alignment in the device fabrication process. 相似文献
49.
S. Horii M. Yamaki H. Ogino T. Maeda J. Shimoyama 《Physica C: Superconductivity and its Applications》2010,470(20):1056-1059
We report the grain-orientation effects under a modulated rotation magnetic field for Y-based cuprate superconductors and LaFeAsO (La1111). Tri-axial orientation has been successfully achieved only for orthorhombic Y2Ba4Cu7Oy and YBa2Cu4O8 powders without a twin microstructure, while separation of three crystallographic axes could not be observed in twinned YBa2Cu3Oy (Y123) and tetragonal La1111 powders. The morphology of grains, in addition to the symmetry of crystal structures, seriously affects the degrees of tri-axial orientation, which means that the control of twin microstructures is required for the tri-axial magnetic orientation in Y123. 相似文献
50.
F. Ogino Professor T. Sakano T. Mizushina Professor Emeritus 《Heat and Mass Transfer》1987,21(2-3):87-93
An analysis and measurement were made of momentum and heat transfers from fully developed turbulent flow in an eccentric annulus to inner and outer tube walls. The eddy diffusivities of momentum and heat obtained in the turbulent flow in a circular tube were applied to the annular flow in the analysis. The result indicates that the calculated friction factor and average Nusselt numbers on the inner and outer tube walls are in fairly good agreement with the measurements. 相似文献