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1.
Huricha Baigude Kaname Katsuraya Kohsaku Okuyama Kenichi Hatanaka Emi Ikeda Naokazu Shibata Toshiyuki Uryu 《Journal of polymer science. Part A, Polymer chemistry》2004,42(6):1400-1414
A novel sugar‐containing poly(ornithine) dendrimer is synthesized for possible antigen delivery and related applications. The dendrimer contains an ornithine dendron as interior scaffolding and oligosaccharides on the periphery, which provide an attachment site for a peptide antigen. Maltose or lactose is bound to both hemispherical and spherical poly(ornithine) dendrimer generation 3 (G3) by reductive amination between its reducing end and the peripheral amino group of the dendrimer using a borane‐pyridine complex in a buffer solution at 50 °C. The degree of substitution of sugar is changed by varying the molar ratio of sugar to dendrimer. When the surface of spherical poly(ornithine) dendrimer G3 is modified by binding β‐alanine to the 16 amino groups, highly substituted maltose‐ or lactose‐β‐alanine‐poly(ornithine) dendrimer G3 is obtained in high yield after 7 days of reaction. The structures of these sugar‐containing dendrimers are characterized by NMR and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry analyses. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1400–1414, 2004 相似文献
2.
Tadafumi Shindo Toshiyuki Uryu 《Journal of polymer science. Part A, Polymer chemistry》1992,30(3):363-370
Solid-state polymerization of a binary mixture of nonliquid-crystalline monomer and liquidcrystalline compound was carried out using electron beam. The monomers were benzoic acid containing 4-[ω-(meth)acryloyloxyalkyloxy] benzoic acids, in which the alkylene spacer was ethylene, hexamethylene, or undecamethylene. The conversion yield of monomer to polymer to a large extent increased with increasing content of a liquid-crystalline compound with a terminal carboxylic group, such as 4-n-alkyloxybenzoic acid, while the addition of a liquid-crystalline compound without terminal carboxylic group did not affect polymerization of the monomer. Phase diagrams of the mixture of monomer and liquid-crystalline compound were examined using cross-polarizing microscopy and differential scanning calorimetry (DSC). All mixtures of monomer and 4-n-alkyloxybenzoic acid or liquid-crystalline compound without terminal carboxylic group showed liquid-crystallinity in a broad composition range. It was concluded that liquid-crystalline compounds with terminal carboxylic acid may form hydrogen bondings with methacrylate or acrylate monomer having terminal carboxylic acid which enhance polymerizability of the mixture. The stereoregularity of polymers determined by NMR depended on increasing irradiation dose and temperature rather than the content of the added liquid-crystalline 4-n-decanoxybenzoic acid. 相似文献
3.
Toshinobu Higashimura Yoshitsugu Hirokawa Kei Matsuzaki Toshiyuki Uryu 《Journal of polymer science. Part A, Polymer chemistry》1980,18(5):1489-1498
Acetal additions to β-substituted vinyl ethers having a variety of substituents (alkenyl ethers) were stereochemically investigated as model reactions for their cationic polymerization. The reactions catalyzed by BF3O(C2H5)2 in CH2Cl2 at O°C gave 1:1 adducts, the steric structure of which was determined by means of 13C-NMR spectroscopy. trans-Alkenyl ethers always gave adducts with a single structure stereospecifically, indicating that the intermediate carbocation attacks a trans-alkenyl ether from a definite direction independent of the bulkiness of substituents. On the other hand, cis-alkenyl ethers formed adducts with two steric structures, and the direction of cation addition was found to depend on the bulkiness of the alkoxy group involved. The above trends were in agreement with the results for poly(alkenyl ether)s and allowed detailed discussion of the stereochemistry of the propagation processes in alkenyl ether polymerizations. 相似文献
4.
Toshiyuki Uryu Toshiyuki Seki Tokiji Kawamura Akashi Funamoto Kei Matsuzaki 《Journal of polymer science. Part A, Polymer chemistry》1976,14(12):3035-3044
The stereoregularity of polystyrene prepared by anionic polymerization was determined by means of 13C-NMR spectroscopy. The stereoregularity changed with such polymerization conditions as catalyst, solvent, and temperature. Sodium naphthalene as catalyst gave a syndiotactic-rich polystyrene of 66–68% syndiotactic dyads independently of solvent and temperature, while potassium and cesium naphthalenes as catalyst produced polystyrenes with different stereoregularities ranging from syndiotactic-rich to isotactic-rich configurations, depending on solvent and temperature. The mechanism of anionic polymerization which caused the difference in stereoregularity was discussed from the viewpoint of growing ionic species. 相似文献
5.
Tamura O Shiro T Ogasawara M Toyao A Ishibashi H 《The Journal of organic chemistry》2005,70(12):4569-4577
The 4-hydroxy 4-substituted glutamic acid moiety is a common substructure of biologically important natural products such as monatin [(2S,4S)-2], lycoperdic acid (3), and dysiherbaine (4). To develop methodology for syntheses of these natural products, cycloadditions of nitrone 5 with 2-substituted 2-propen-1-ols 6 and 2-substituted acrylates 8 were investigated. Reactions of nitrone 5 with alcohols 6 in the presence of MgBr2OEt2 gave cycloadducts 7 in a highly stereoselective manner, whereas noncatalyzed reactions of 5 with acrylates 8 afforded adducts 9. Using the former reaction, syntheses of monatin [(2S,4S)-2], monatin derivative 18, and lycoperdic acid (3) were accomplished. The C4-epimer of monatin [(2S,4R)-2)] was also synthesized by employing the latter cycloaddition. 相似文献
6.
Yen-Yuan Chen Ryuichi Oshima Kenichi Hatanaka Toshiyuki Uryu 《Journal of polymer science. Part A, Polymer chemistry》1986,24(7):1539-1550
We report herein studies of grafting of MMA onto (1 → 5)-α-D -ribofuranan and (1 → 5)-α-D -xylofuranan by ceric ion initiation both in water and in dimethyl sulfoxide (DMSO). In aqueous medium, the graft polymer having high grafting (%) can be obtained easily without adding any nitric acid. The degradation of polysaccharide by the acidic ceric ion solution is not serious; 73–82% of its original molecular weight remained after the polymerization. In DMSO, graft polymers having lower grafting (%) and lower molecular weight of grafts were obtained. 相似文献
7.
Mizuho Nisizawa 《Journal of polymer science. Part A, Polymer chemistry》1969,7(5):1247-1254
When protein is irradiated by γ-rays from a 60Co source in various liquids containing aromatic hydrocarbons, such as benzene, naphthalene, and phenanthrene, the effect of the radiation varies with the irradiation liquids containing aromatic hydrocarbons. An empirical equation for the viscosity change was obtained. Protein irradiated by γ-rays from a 60Co source in air showed the effect of pH on protein reactions. An empirical equation for the viscosity change was obtained. 相似文献
8.
The catalytic oxidation of glucose on Pt electrodes modified by adsorbed metals was studied in 1 M HClO4 by linear sweep voltammetry. The adsorbed metals (denoted as Mad, such as Biad and Pbad) formed on Pt in the potential region more positive than the reversible potential of an M=+/Mo couple, lead to a marked increase in the anodic c?urrent of glucose by about one order of magnitude. The catalytic activity depends on the surface coverage by the Mad. The strongly adsorbed species of lactone type, which are responsible for blocking the successive oxidation, are formed on the electrode surface in the anodic processes of glucose on a bare Pt electrode. The formation of such poisonous species is accelerated in the presence of adsorbed hydrogen on Pt. The effects of Mad were discussed on the basis that Mad plays its major role on the Pt electrode surface in removal of the adsorbed hydrogen which initiates the formation of the poisonous species. 相似文献
9.
The catalytic effects of metal ions on the anodic oxidation of ascorbic acid on a Pt electrode in 1 M HClO4 were studied by linear sweep voltammetry. The anodic peak due to a two-electron oxidation of ascorbic acid shifts to the negative potential side on the addition of Bi3+. This indicates the accelerating effect of Bi3+ on the oxidation of ascorbic acid. The presence of other metal ions, such as Pb2+, Hg2+, Tl+, Ag+ and Sb3+, also exerts similar effects. These metal ions were adsorbed on a Pt electrode at underpotentials and the adsorbed metals (denoted as Mad) still remain on the electrode surface until the electrode potential goes up to and beyond the peak potential of the oxidation of ascorbic acid. On the other hand, metal ions forming no adsorbed layer on Pt, such as Co2+, Zn2+, Fe3+ and Ni2+, exhibit no catalytic effect. These facts suggest that the presence of a Mad on Pt is essential for the promotion of the anodic oxidation of ascorbic acid. However, there is a difference in the catalytic action among the Mad, for example, Cuad, Cdad, Inad, Snad and Moad display no catalytic action.The catalytic activity depends on the degree of surface coverage by the Mad. The maximal effect of the Mad is attained in the submonolayer region. The effects of metal ions were discussed on the basis that the Mad plays its major role in the removal of the adsorbed ascorbic acid occupying active sites on the electrode surface, and provides effective sites for the activation of adjacent water molecules. Furthermore, from the 13C NMR spectra for the oxidation products, the adsorbed water on the Mad appears to function by promoting the subsequent hydration steps, following the electron-transfer step of ascorbic acid. 相似文献
10.
Yozo Kosaka Toshiyuki Uryu 《Journal of polymer science. Part A, Polymer chemistry》1995,33(13):2221-2232
Side-chain liquid-crystalline copolymers and polymer blends containing an electron-donating (carbazolylmethylene)aniline group and electron-accepting nitrophenyl groups with various central linking groups between aromatic groups in the mesogenic units, i.e., N?CH, CH?CH, N?N, and COO, were prepared to examine effects of the mesogenic structure on thermal behaviours. The most remarkable effects of the central linking group on the thermal properties and the miscibility were observed for the polymer blends. The 1:1 miscible polymer blends were prepared from the electron-donating polymer containing (carbazolylmethylene)aniline group (PM6Cz) and the electron-accepting polymers with similar central linking groups, i.e., N?CH, CH?CH, and N?N. For example, the 1: 1 polymer blend of PM6Cz and the electron-accepting polymer containing the nitrostilbene group induced a smectic phase from 73 to 207°C. This isotropic temperature was 46°C higher than the calculated value (161°C) based on the composition without the electron donor-acceptor interaction. On the other hand, the 1: 1 polymer blend of PM6Cz and the electron-accepting polymer containing the nitrophenylbenzoate group showed phase separation. Thus, the remarkable thermal stability and the miscibility of the polymer blends containing the electron donor and acceptor groups might be caused by planar structures between the mesogenic side groups which have similar central linking groups through the electron donor-acceptor interaction. A similar tendency was seen for copolymers and binary mixtures of both low-molecular-weight compounds containing the same mesogenic groups. © 1995 John Wiley & Sons, Inc. 相似文献