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排序方式: 共有182条查询结果,搜索用时 15 毫秒
1.
Akira Matsumoto Hisako Mano Masayoshi Oiwa George B. Butler 《Journal of polymer science. Part A, Polymer chemistry》1989,27(6):1811-1816
The radical polymerization of tetraallyl ammonium chloride (TAAC) was carried out in water using azo-initiator as compared to that of diallyl dimethyl ammonium chloride (DADMAC); the rate of polymerization was quite low for TAAC, around one-third of DADMAC. Kinetic discussion revealed the importance of degradative chain transfer in the polymerization of TAAC. The cyclopolymerizability of TAAC was estimated kinetically as the ability of 5-membered monocyclic radical to form a bicyclic ring, giving the cyclization constant of 21 mol/L at [M] = 2 mol/L. Gelation occurred at around 20% conversion. 相似文献
2.
Yoshinori Tominaga Hiroto Okuda Shinya Kohra Hisako Mazume 《Journal of heterocyclic chemistry》1991,28(5):1245-1255
Reaction of various types of enaminones, which are prepared by the condensation of 1,3-dicarbonyl compounds with aromatic amines, with carbon disulfide in the presence of sodium hydroxide as the base in dimethyl sulfoxide to give the corresponding enamino dithiocarboxylates, 1,3-thiazines and trithiones. Enamino dithiocarboxylates are cyclized under refluxing in diphenyl ether to give the fused quinoline derivatives. The reaction of 6-arylamino-1,3-dimethyluracils with excess carbon disulfide in the presence of sodium hydroxide and subsequent methylation with dimethyl sulfate gave directly the corresponding 1,3-dimethyl-5-methylthiopyrimido[4,5-b]quinoline-2,4(1H,3H)-diones. 相似文献
3.
The chelation controlled radical reactions of ethyl γ-benzyloxy-α-methylenecarboxylates bearing a bulky γ-substituent, such as CHMe2, CHPh2, c-C6H11 and CH(Ph)OTBDMS, with alkyl iodides gave the syn-adducts with high diastereoselectivities. However, the diastereoselectivity for the substrates bearing a γ-substituent CH(i-Pr)OTBDMS depended critically on the configuration of the substituent; the substrate bearing the OTBDMS group anti to the γ-benzyloxy group showed poor diastereoselectivity, but its diastereomer gave syn-adduct exclusively. The high syn-selectivitiy is referred to the H-atom transfer to the outside face of radical center in the sharply folded seven-membered chelate intermediate bearing the ethoxy group with Z-geometry. The corner flapping of the radical center atom of the global minimum energy conformer generates a local minimum conformer and the H-atom transfer to the outside face of the radical center of the newly formed structure gives the anti-adduct. The poor diastereoselectivity is due to the very small energy difference between the two conformers and consequently both the syn- and anti-adducts are yielded in nearly equal amounts. 相似文献
4.
5.
Yoshinori Tominaga Syuichirou Ohno Shinya Kohra Hiroshi Fujito Hisako Mazurae 《Journal of heterocyclic chemistry》1991,28(4):1039-1042
N-Bis(methylthio)methylenecyanamide ( 1 ) was allowed to react with active methylene compounds (methyl cyanoacetate, dimethyl malonate, ethyl acetoacetate, ethyl phenylacetate) in the presence of potassium carbonate or potassium hydroxide in dimethyl sulfoxide followed by the treatment using appropriate a base or an acid to give the corresponding 6-methylthiouracil derivatives in 15–80% yields. These uracil derivatives are found to be useful intermediates for the synthesis of 6-aminouracils and fused pyrimidine derivatives. 相似文献
6.
Prof. Dr. Akira Watanabe Dr. Hisako Tamai Mrs. Kyoko Hayashi 《Colloid and polymer science》1977,255(8):773-781
Summary The adsorption of ionic dyes, the builder effect, and the interaction between ionic dyes and surface active agents were investigated by using the electrocapillarity at oil/water interfaces. The oil phase was the solution of tetra-butylammonium chloride, sodium cetylsulphate, cetylpyridinium chloride or stearylamine in methylisobutylketone, and the water phase contained various dyes in addition to the inorganic electrolyte. The interfacial tension decreased over the anodic (or cathodic) polarization range, when anionic (or cationic) dyes were added to the water phase, thus indicating the dye adsorption at the interface. The interfacial excess of dye ions was found to increase linearly with the cubic roots of dye concentration and of ionic strength of the water phase. The counterion binding took place at the oil/water interface between anionic (or cationic) dyes and positive (or negative) head groups of surface active agent ions adsorbed at the interface. It was found that the equilibrium constants of binding between anionic dyes and cationic surface active agents at the oil/water interface were of the same order of magnitude as, and a little larger than, those obtained at the water bulk phase.
With 12 figures and 2 tables 相似文献
Zusammenfassung An Öl-Wasser-Grenzflächen wurde die Adsorption ionischer Farbstoffe, die Füllerwirkung und die Wechselwirkung zwischen ionischen Farbstoffen und grenzflächenaktiven Verbindungen mit Hilfe der Elektrokapillarität untersucht. Die Ölphase bestand aus einer Lösung von Tetrabutylammoniumchlorid, Natriumcetylsulfat und Cetylpyridiniumchlorid oder Stearylamin in Methylisobutylketon. Die wässerige Phase enthielt verschiedene Farbstoffe und anorganische Elektrolyte. Die Grenzflächenspannung wurde durch anodische (bzw. kathodische) Polarisation erniedrigt, wenn anionischer (bzw. kationischer) Farbstoff zur Wasserphase gegeben wurde. Dies zeigt an, daß Farbstoff an der Grenzfläche adsorbiert wird. Die Grenzflächenkonzentration des Farbstoffions nimmt linear mit der Kubikwurzel der Farbstoffkonzentration und mit der Ionenstärke zu. Als Gegenionen für die anionischen (bzw. kationischen) Farbstoffe an der Grenzfläche wirken die positiven (bzw. negativen) Endgruppen der Tenside, die ebenfalls in der Grenzschicht adsorbiert sind. Die Gleichgewichtskonstanten für die Wechselwirkung zwischen den ionischen Farbstoffen und den grenzflächenaktiven Verbindungen sind an der Öl-Wasser-Grenzfläche von der gleichen Größenordnung bzw. geringfügig größer als in der wässerigen Volumenphase.
With 12 figures and 2 tables 相似文献
7.
The lankacidin biosynthetic gene cluster in Streptomyces rochei strain 7434AN4 was found to span 31 kb of the giant linear plasmid pSLA2-L and contain a polyketide synthase (PKS)/nonribosomal peptide synthetase (NRPS) hybrid gene (lkcA), type I PKS genes, and pyrroloquinoline quinone (PQQ) biosynthetic genes (lkcK-lkcO). Feeding of PQQ to a pqq mutant restored the lankacidin production, suggesting its crucial role in an oxidation process. However, formation of the 17-membered macrocyclic ring was not catalyzed by PQQ-dependent dehydrogenase (Orf23), but was by flavin-dependent amine oxidase (LkcE). Compound LC-KA05 isolated from an lkcE disruptant was an acyclic intermediate lacking the C2-C18 linkage. These results suggested a cyclization mechanism for the synthesis of the lankacidin macrocyclic skeleton. 相似文献
8.
Tetsuro Shimo Shinichi Yamasaki Kenichi Date Hisako Uemura Kenichi Somekawa 《Journal of heterocyclic chemistry》1993,30(2):419-423
Photosensitized cycloaddition of 4,6-dimethyl-2-pyrone ( 1 ) with methacrylonitrile ( 3b ) afforded two types of [2 + 2]cycloadducts, 4b and 6b , across the C5-C6 and C3-C4 double bonds in 1 , respectively. Photosensitized reactions of 1 with dimethyl maleate and dimethyl cyclobutene-1,2-dicarboxylate gave [2 + 2]cycload-ducts 4d, 4e across the C5-C6 double bond, in addition to [4 + 2]cycloadduct 9d or bicyclo[4.2.0]octadiene 10e . The photoreactions of methyl 2-pyrone-5-carboxylate ( 2 ) with 3b and 2-chloroacrylonitrile ( 3c ) gave [4 + 2]cycloadducts 5b, 5c in addition to [2 + 2]cycloadducts 11b and 11c across the C5-C6 double bond in 2 . The photocycloaddition mechanism was explained from results calculated by means of PM3-CI method. Namely, the site- and/or regio-selective products, 4, 5, 8, 9 and 10 were thought to come from the same site-selective radical intermediates in the case of electron-poor olefins. Pyrolysis and/or hydrolysis of the cycload-ducts 4e, 5b, 5c gave 5,6-dihydro-2-pyrone 12 or benzene derivatives. 相似文献
9.
10.
Hirosato Monobe Shoji Mima Takushi Sugino Yo Shimizu Masakatsu Ukon 《Liquid crystals》2013,40(8):1253-1258
The orientational behaviour of the nematic discotic phase of 2,3,6,7,10,11-hexa(4-n-octyloxybenzoyloxy)triphenylene (C8OBT) on substrates coated with a polyimide or cetyltrimethylammonium bromide (CTAB) was investigated by polarizing optical microscopy. The averaged order parameters and directions of the triphenylene core and the carbonyl groups of C8OBT were evaluated by an infrared dichroic method. The discotic nematic (ND) phase of C8OBT exhibits a homeotropic alignment on a polyimide film, a typical nematic schlieren texture on a glass substrate, and a tilted or planar homogeneous alignment on a CTAB-coated substrate. The order parameter of the triphenylene core is higher on a polyimide film (S = 0.6) than on a CTAB-coated substrate (S = 0.2), whereas that of the carbonyl groups remains roughly constant at 0.2 to 0.3 independent of the substrate for the ND phase. 相似文献