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991.
Fumio Yoneda Masakazu Koga Kiyoshi Tanaka Yumihiko Yano 《Journal of heterocyclic chemistry》1989,26(5):1221-1228
Cyclization of N, N′-dialkyl-N-(3-methyluracil-6-yl)-N′-(5-nitro-3-methyluracil-6-yl)- p-phenylenediamines with the Vilsmeier reagent gives the corresponding 1,3,6,8,10,11,14-heptaazapentaphene-2,4,7,9-(14H,3H,8H,-11H) -tetrones (angular mixed flavins) 2. Cyclization of N, N′-di(5-nitro-3-methyluracil-6-yl)-p-phenylenedi-amines with the Vilsmeier reagent gives the corresponding 1,3,5,6,8,10,11,14-octaazapentaphene-2,4,7,9-(14H,3H,8H,11H)-tetrones (angular doubled flavins) 11 along with the angular mixed flavins 2. 相似文献
992.
A sensitive assay for guanase activity in human serum (10 μl) is described. Xanthine, formed enzymatically from the substrate guanine, is determined in a flow system in which columns of immobilized xanthine oxidase, uricase and horseradish peroxidase are connected in that sequence in the flow line. Hydrogen peroxide formed in the enzymatic conversion of xanthine is measured fluorimetrically by reaction with 3-(p-hydroxyphenyl)-proprionic acid in the system. Linear calibration graphs are obtained for 0.52-500 pmol of xanthine in the 20-μl sample injected. This method permits the assay of guanase activity in the sera of healthy persons and patients with hepatitis. 相似文献
993.
Rokuya Yamashita Kiyoshi Kikukawa Fumio Wada Tsutomu Matsuda 《Journal of organometallic chemistry》1980,201(2):463-468
The title complex, [ArN2Pd(PPh3)3]PF6(Ar = 4-methoxyphenyl), was prepared by the reaction of ArN2PF6 with (PPh3)4Pdo. Other ArN2X (Ar = phenyl, 4-tolyl, 4-fluorophenyl, 2,4,6-trichlorophenyl; X = BF4, PF6) gave a mixture of aryldiazenido and arylpalladium complexes. The aryldiazenido complexes decompose to arylpalladium compounds at room temperature, UV irradiation facilitates this decomposition. 相似文献
994.
The asymmetric reaction of a lithium enolate generated from a BHA (2, 6-di-tert-buty-4-methoxyphenyl) propanoate was allowed to react with benzaldehyde in the presence of a diether-type chiral ligand affording the corresponding anti-aldol product in a moderate enantioselectivity. A tetradentate ligand induced better enantioselectivity albeit relative loss of anti-selectivity. A variation of lithiating amide agent affected the selectivity, indicating involvement of an amine as a component of the mixed aggregate. Absolute configuration of some of the aldol products was determined by standard transformations. 相似文献
995.
Kiyoshi Matsumoto Takane Uchida Kinuyo Aoyama Masahiko Nishikawa Takeshi Kuroda Tadashi Okamoto 《Journal of heterocyclic chemistry》1988,25(6):1793-1801
With the intention that annulation of carbo- or heteroaromatic rings at the 1,2-positions can activate 3-cyanoindolizines as 1,3-dipolar species, 6-cyanobenz[a]indolizines, pyridazino[4,5-a]indolizines and 5-cyano-1,3-diphenylthiopheno[3,4-a]indolizine were prepared. 6-Cyanobenz[a]indolizines smoothly -underwent 1,3-dipolar cycloaddition on to dibenzoylacetylene and diacetylacetylene to afford the corresponding indolizino[3,4,5-ab]isoindoles, whereas 5-cyano-1,4-diphenylpyridazino[4,5-a]indolizine reacted with dimethyl acetylenedicarboxylate to give the 1:2 adduct. Only a 3% yield of 5-cyano-1,3-diphenylthiopheno[3,4-a]indolizine formed upon phosphorus pentasulfide treatment of 1,2-dibenzoyl-3-cyanoindolizine. 相似文献
996.
The results of the experimental studies on the solvent effects upon the fluorescence and the absorption spectra of carbazole and indole are described, which makes it possible to estimate the difference of the electronic structures in the fluorescence state from those in the ground state.The electronic structures of the molecules are studied theoretically on the basis of the experimental results.
Zusammenfassung Die Beeinflussung der Absorptions- bzw. Fluoreszenzspektren von Carbazol und Indol durch Lösungsmitteleffekte wird untersucht. Aus den Ergebnissen werden Rückschlüsse auf die Elektronenstrukturen der Grund- und Fluoreszenzzustände gezogen. Eine auf den experimentellen Resultaten basierende theoretische Behandlung der Elektronenstrukturen schließt sich an.
Résumé Nous avons étudié les effects de solvant sur les spectres d'émission et d'absorption du carbazol et de l'indole. Les résultats permettent des conclusions sur la différence entre les structures électroniques des états excité et fondamental. Des calculs sur ces structures sont faits à l'aide des données expérimentales.相似文献
997.
The electrochemical kinetic parameters of the V(II)/V(III) couple in HBr solutions of different concentrations were determined from the measurement of faradaic impedance as a function of time during the growth of the dropping mercury electrode. The same method of analysis was applied to the study of the effect of uncharged surfactants on the electrode reaction of Cd(II) in 1 M NaNO3 solutions. The rate constant of the vanadium system decreased with increasing concentration of HBr; this change of the rate constant was discussed in terms of the Frumkin double-layer effect. The relationship between the rate constant of Cd(II) and coverage of the surfactants was not linear, and followed the equation based upon Parsons' model of the blocking effect. The conditional rate constant of Cd(II) in the absence of surfactants was determined to be 0.6–1.1 cm s?1 from the dependence of the rate constant on the coverage. 相似文献
998.
Tsuneo Suzuki Kiyoshi Tanemura Takaaki Horaguchi Takahachi Shimizu Tohru Sakakibara 《Journal of heterocyclic chemistry》1992,29(2):423-429
By treatment of ethyl 4- or 5-substituted 2-acetylphenoxyacetates 1 with potassium hydroxide in dry dioxane, benzofurans 2–7 and 2,3,4,5-tetrahydro-1-benzoxepin-3,5-diones 8 were obtained. The relative yields of benzofurans 2–7 and 2,3,4,5-tetrahydro-1-benzoxepin-3,5-diones 8 varied with the types of 4- or 5-substituents. The electron-donating 4-methoxyl group favored the formation of benzoxepins. On the other hand, electron-withdrawing substituents such as the 4-nitro group favored the formation of benzofurans. When esters 1 were treated with sodium amide, 2,3-dihydrobenzofurans 2 were obtained exclusively regardless of 4- or 5-substituents. 相似文献
999.
Yukio Nagaosa Kiyoshi Horita Seiichi Nishimoto 《Fresenius' Journal of Analytical Chemistry》1992,342(9):698-701
Summary Physico-chemical parameters of various organic solvents, such as conductivity, viscosity, available potential range and phase-separation characteristics, have been evaluated for the use of direct polarographic analysis after liquid-liquid extracxtion. Due to its higher conductivity of 1.16 mS cm–1 and a wide available potential range of 0.81 –1.72 V vs. Ag/AgCl, a dichloromethane solution containing 0.1 mol/l tetrabutylammonium perchlorate is chosen as the best organic solvent solution for the purpose of this study. Bismuth(III) is extracted into the organic phase and gives well-defined anodic and cathodic waves at –0.12 V and –0.51 V, respectively. A selective polarographic determination of the metal after the dichloromethane extraction has been developed. 相似文献
1000.
A new method to assay alkaline and acid phosphatases assay using ascorbic acid 2-phosphate (AsA-P) and ditetrazolium salt nitroblue tetrazolium chloride (NBT) was developed. AsA-P is hydrolyzed in the presence of phosphatase to yield ascorbic acid. In turn, the ascorbic acid reduces NBT directly or indirectly, opening the tetrazole ring to produce an insoluble formazan as a colored precipitate. The proposed method for alkaline phosphatase was compared with a conventional method in which 5-bromo-4-chloro-3-indolyl phosphate (BCIP) is used in combination with NBT in the dot blots of a dilution series of β-lactoglobulin. AsA-P reduced NBT more effectively than BCIP in the presence of alkaline phosphatase. AsA-P could be also used as the chromogenic substrate for an acid phosphatase assay in the presence of phenazinium methylsulfate and NBT. 相似文献