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51.
Eietsu Hasegawa Shinya Takizawa Akira Yamaguchi Naoki Chiba Hiroshi Ikeda 《Tetrahedron》2006,62(27):6581-6588
Photoinduced electron-transfer reactions of several ketone substrates were studied to evaluate the utilities of 1,6-bis(dimethylamino)pyrene (BDMAP), 1,6-dimethoxypyrene (DMP), 9,10-bis(dimethylamino)anthracene (BDMAA), and 9,10-dimethoxyanthracene (DMA) as electron-donating sensitizers cooperating with 2-aryl-1,3-dimethylbenzimidazolines. BDMAP and DMP generally led higher conversion of ketones and better yield of reduction products compared to BDMAA and DMA. 相似文献
52.
Yukihiro Shintani Keiji Hirako Masanori Motokawa Yoshihiko Takano Masahiro Furuno Hiroyoshi Minakuchi Mitsuyoshi Ueda 《Analytical sciences》2004,20(12):1721-1723
An interconnecting technique, the "PDMS connection method", for quartz microchips in a high-pressure system is presented. The connection between quartz microchips is an essential technology for modular microfluidic devices, such as microchip-HPLC. PDMS was applied to the seal material, being spread on the seal side of the chips, and set into the metal housing. The characteristics of the PDMS connection method concerning pressure resistance and the extension of the peak were examined. The experimental results showed a good seal at 5 MPa, which seem to be sufficient for realizing microchip-HPLC utilizing a monolithic silica capillary column as a separation medium. The influence of the extra column effect on chromatographic separation was almost the same as in the case using a commercial union fitting. In addition, the PDMS connection enabled the detachability of chip-based modules with user-friendliness. Our experimental findings suggest that the novel PDMS connection method can possibly be applied as a generic technology in high-pressure microTAS. 相似文献
53.
Yoshihiko Kondo Ken Endo Nobuhiko Iki Sotaro Miyano Fumio Hamada 《Journal of inclusion phenomena and macrocyclic chemistry》2005,52(1-2):45-49
Even though it was obtained in poor yield, p-tert-butylthiacalix[8]arene (TC8A) has been synthesized as a new member of thiacalix[n]arenes by the terephthalate-induced cyclization of a mixture of acyclic oligomers, which was obtained by the reaction between p-tert-butylphenol and sulfur with CaO in ethylene glycol/diphenyl ether system. Slow evaporation of the chloroform solution of TC8A afforded guest-free crystals consisting of TC8A itself. The close-packed crystal structure of TC8A resembles that of p-tert-butylcalix[8]arene (C8A) closely, containing a plated loop molecular structure.This revised version was published online in July 2005 with a corrected issue number. 相似文献
54.
55.
This paper is concerned with the comparison between mechanical properties of polymer composite system and those of each individual constituent. The comparison is mainly performed with respect to the viscoelastic Young's modulus and the relaxation Young's modulus. These mechanical constants may be obtained from the correspondence principle by applying the Laplace transform to the constitutive equation. The calculated results exhibit that the mechanical property of polymer composite system strongly depends on that of matrix with respect to frequency- and time-dependences. That is, as for the vibration and dynamic response in the steady state, the frequency-dependence of peak position about imaginary part of dynamic modulus of composite system is similar to that of matrix, while the magnitude of dynamic modulus depends on volume fraction of dispersed particles to total volume. As for the stress relaxation, the time-dependence of the relaxation Young's modulus of composite system resemble that of matrix each other, while the magnitude depends on the volume fraction of dispersed particles to total volume. This is due to the calculating condition that particle is assumed to be very rigid in comparison with matrix in this paper. 相似文献
56.
Sodium poly(styrenesulfonate)(polySSNa)-grafted polymer nanoparticles were synthesized by core-cross-linking of block copolymer micelles and subsequent chemical transformation. Block copolymers, poly(p-((1-methyl)silacyclobutyl)styrene-block-poly(neopentyl p-styrenesulfonate)s, polySBS-b-polySSPen, were synthesized by nitroxy-mediated living radical polymerization. The block copolymers formed micelles (Rh=15-23 nm, where Rh represents the hydrodynamic radius) with a polySBS core and polySSPen shell in acetone. The micelle core was cross-linked by ring-opening polymerization of silacyclobutyl groups in polySBS. Hydrolysis of the neopentyl groups provided polySSNa-grafted nanoparticles. The Rh of the particles before the hydrolysis ranged from 12 to 21 nm in acetone, while they varied to the range from 50 to 110 nm in water after the hydrolysis. 相似文献
57.
58.
Yoshihiko Taguchi Yasuyuki Ishida Hajime Ohtani Hiroyuki Bekku Masaya Sera 《Analytical sciences》2004,20(3):495-499
A polymeric hindered amine light stabilizer (HALS), Tinuvin 622 (MW [symbol: see text] 4000), in PP materials formulated with a magnesium hydroxide flame retardant was determined by reactive thermal desorption (RTD) gas chromatography (GC). Two kinds of the HALS components that were formed through the RTD in the presence of tetramethylammonium hydroxide [(CH3)4NOH, TMAH] were clearly observed in the chromatograms of the PP samples, with negligible interference from the other additives and the PP substrate. Here, the coexisting flame retardant was proved to affect significantly the RTD process of the occluded HALS. As a result, the recovery of the HALS components in the RTD-GC chromatograms of the PP samples increased with increase in the content of the flame retardant. This enhancement of the HALS recovery is attributed mainly to the preferential exposure of the HALS on the surface of the ground PP sample through the interaction between the polymeric HALS and the flame retardant in the molten PP during kneading. In spite of such a considerable action of the flame retardant, the observed intensities of the characteristic peaks of HALS by RTD-GC showed a good linear relationship with the HALS content in the PP samples with constant content of the flame retardant (50 phr); this relationship could be used as the calibration line for the determination of the polymeric HALS in the PP materials containing the flame retardant. 相似文献
59.
The synthetic procedures for spilanthol and trail-following pheromone for a southern subterranean termite were described. The syntheses heavily depend on the new diene synthesis using titanium reagent. 相似文献
60.
CuBr2-catalyzed three-component coupling of N-benzylallylamine, ethyl glyoxalate, and terminal alkynes afforded glycinate-tethered 1,6-enynes, which were further transformed into polycyclic pyrrole-2-carboxylates via iridium-catalyzed cycloisomerization/Diels-Alder cycloaddition/dehydrogenation sequence under conventional and microwave heating conditions. The corresponding β-amino acid analogues were obtained from the Ir-catalyzed reaction of enynes prepared from lithium amides of allylamines with methyl non-2-en-4-ynoate. The Cu-catalyzed Mannich-type condensation was further extended to the synthesis of the glycinate-tethered dienyne and cyclopropylenyne, which were subjected to Rh-catalyzed cycloisomerizations to furnish bicyclic amino acids. 相似文献