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191.
Akira Hirao Masahiro Kitamura Mayumi Hayashi Surapich Loykulnant Kenji Sugiyama 《Macromolecular Symposia》2005,226(1):35-50
Anionic polymerizations of four new dual-functionalized styrene and α-methylstyrene derivatives, 3-(4-(4-isopropenylphenoxy)butyl)styrene ( 4 ), 3-(4-(2-isopropenylphenoxy)butyl)-α-methylstyrene ( 5 ), 4-(4-(4-isopropenylphenoxy)butyl)-α-methylstyrene ( 6 ), and 4-(4-(2-vinylphenoxy)butyl)styrene ( 7 ), were carried out in THF at -78 °C with sec-BuLi as an initiator. Both 4 and 5 underwent anionic polymerization in a living manner to quantitatively afford functionalized polystyrenes and poly(α-methylstyrene)s having α-methylstyrene moiety in each monomer unit and precisely controlled chain lengths. On the other hand, insoluble polymers were obtained by the anionic polymerization of 6 and 7 under the same conditions. The positional effect of substituent on anionic polymerization was discussed. 相似文献
192.
Preparation and characterization of high-specific-surface-area activated carbons from K2CO3-treated waste polyurethane 总被引:2,自引:0,他引:2
Hayashi J Yamamoto N Horikawa T Muroyama K Gomes VG 《Journal of colloid and interface science》2005,290(2):437-443
An activated carbon with high specific surface area was prepared from polyurethane foam by chemical activation with K2CO3 and the influences of carbonization temperature and impregnation ratio on the pore structure of the prepared activated carbon were investigated. It was found that the specific surface area of the activated carbon was at a maximum value (about 2800 m(2)/g) at a carbonization temperature of 1073 K and at an impregnation ratio of 1.0. It was concluded that the polyurethane foam structure was modified during impregnation by K2CO3, K2CO3 promoted charring during carbonization, and then the weight loss behavior was changed below 700 and above 1000 K, carbon in the char was consumed by K2CO3 reduction, and this led to the high specific surface area. The prepared activated carbon had a very sharp micropore size distribution, compared with the commercial activated carbon having high specific surface area. The amounts of three organic vapors (benzene, acetone, and octane) adsorbed on the prepared activated carbons was much larger than those on the traditional coconut shell AC and the same as those on the commercial activated carbon except for octane. We surmised that the high specific surface area was due to the modification of the carbonization behavior of polyurethane foam by K2CO3. 相似文献
193.
Tsubaki H Tohyama S Koike K Saitoh H Ishitani O 《Dalton transactions (Cambridge, England : 2003)》2005,(2):385-395
Intramolecular pi-pi and CH-pi interactions between the bpy and PR3 ligands of fac-[Re(bpy)(CO)3(PR3)]+ affect their structure, and electrochemical and spectroscopic properties. Intramolecular CH-pi interaction was observed between the alkyl groups on the phosphine ligand (R =nBu, Et) and the bpy ligand, and intramolecular pi-pi and CH-pi interactions were both observed between the aryl group(s) on the phosphorus ligand (R =p-MeOPh, p-MePh, Ph, p-FPh, OPh) and the bpy ligand, while no such interactions were found in the trialkylphosphite complexes (R = OiPr, OEt, OMe). The intramolecular interactions distort the pyridine rings of the bpy ligand as long as 3.7 x 10(-2)A in crystals. Molecular orbital calculations of the bpy ligand suggest that this distortion decreases the energy gap between its pi and pi* orbitals. An absorption band attributed to the pi-pi*(bpy) transition of the distorted rhenium complexes, measured in a KBr pellet, was red-shifted by 1-5 nm compared to the complexes without the distorted bpy ligand. Even in solution, similar red shifts of the pi-pi*(bpy) absorption were observed. The redox potential E1/2(bpy/bpy*-) of the complexes with the trialkylphosphine and triarylphosphine ligand are shifted positively by 110-120 mV and 60-80 mV respectively, compared with those derived from the electron-attracting property of the phosphorus ligand. In contrast with these properties, three nu(CO) IR bands, which are sensitive to the electron density on the central rhenium because of pi-back bonding, were shifted to higher energy, and a Re(I/II)-based oxidation wave was observed at a more positive potential according to the electron-attracting property of the phosphorus ligand. 相似文献
194.
Novel chiral phosphonoacetates bearing a stereogenic phosphorus atom were successfully synthesized by enzyme-catalyzed kinetic resolution of racemic phosphonoacetates. 相似文献
195.
Kitazaki T Tasaka A Tamura N Matsushita Y Hosono H Hayashi R Okonogi K Itoh K 《Chemical & pharmaceutical bulletin》1999,47(3):351-359
New optically active antifungal azoles, 1-[(1R,2R)-2-(2,4-difluoro- and 2-fluorophenyl)-2-hydroxy-1-methyl-3-(1H-1,2,4-triazol-1-yl)propyl ]-3-(4- substituted phenyl)-2(1H,3H)-imidazolones (1,2) and 2-imidazolidinones (3,4), were prepared in a stereocontrolled manner from (1S)-1-[(2R)-2-(2,4- difluoro- and 2-fluorophenyl)-2-oxiranyl]ethanols (15, 16). Compounds 1-4 showed potent antifungal activity against Candida albicans in vitro and in vivo, as well as a broad antifungal spectrum for various fungi in vitro. Furthermore, the imidazolidinones, 3b--e and 4d, e, were found to exert extremely strong growth-inhibitory activity against Aspergillus fumigatus. 相似文献
196.
Hiromu Hayashi 《Catalysis Surveys from Japan》1999,3(1):43-52
Additive telluromolybdates, MoO3·2TeO2 and MIIO·TeO2·MoO3 (MIITeMoO6; MII = Co, Mn, Zn), converted ethyl lactate selectively to pyruvate in a vaporphase fixedbed flow system at 250–300 °C. A synergy in activity was observed for binary TeO2–MoO3, and crystalline Te2MoO7 was suggested as the active species. The Rietveld analysis of powder XRD patterns of ternary CoTeMoO6 revealed the layer structure quite different from that of the reference Te2MoO7, but tellurium was again located adjacent to molybdenum linked through lattice oxygen. 相似文献
197.
198.
199.
Tomihiro Nishiyama Shigeki Matsui Fukiko Yamada 《Journal of heterocyclic chemistry》1986,23(5):1427-1429
Heterocyclic compounds of four 5-methyl-3-phenyl-1,3-oxazolidin-2-ones have been synthesized by the reaction of N-2-hydroxyethyl- or N-2-hydroxypropylanilines with phosgene in the presence of pyridine. From the spectral behavior, the title compounds are found to exist in the trans and cis forms. 相似文献
200.
Tomio Shimizu Yoshiyuki Hayashi Takehiro Taniguchi Kazuhiro Teramura 《Tetrahedron》1985,41(4):727-738
A variety of symmetrically or unsymmetrically 3,4-disubstituttd furoxans such as dicyano, dialkyl, diacyl, bis(phenylsulfonyl), N.N'-dialkyldicarbamoyl, 3(or 4)-methyl-4(or -3)-phenyl(or nitro, ethoxy, phenoxy, phenylthio, pyrrolidinyl, phenylsulfonyl), 3(or 4)-ethyl-4(or -3)phcnyl, and 3(or 4)-ethoxy-4(or -3)-phenylsulfonylruroxan reacted with dipolarophiles in toluene or xylene at the refluxing temperature to give nitrone-type 1,3-dipolar cycloadducts, 5-substituted 1-aza-2,8-dioxabicyclo-[3.3.0]octanes and/or 3-substituted 2-isoxazoline 2-oxides. On the other hand, some of the furoxans gave 2-isoxazolines via nitrile oxide 1,3-dipolar cycloaddition in a toluene (or xylene)-DMF solvent at the refluxing temperature. 相似文献