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41.
Yoshihisa Kurasawa Tomoyoshi Hosaka Kazue Ikeda Yuko Matsumoto Aiko Ishikura Atsushi Takada Ho Sik Kim Yoshihisa Okamoto 《Journal of heterocyclic chemistry》1994,31(2):527-533
The 3-(arylhydrazono)methyl-2-oxo-1,2-dihydroquinoxalines 9–11 were synthesized by the reaction of the quinoxalines 6–8 with various p-substituted benzenediazonium salts. Compounds 9–11 showed the tautomeric equilibria between the hydrazone imine A and diazenyl enamine B forms in dimethyl sulfoxide media. The substituent effect on the tautomer ratios of A to B was studied by the nmr spectroscopy to clarify that the presence of the ester group R2 on the hydrazone carbon and electron-donating p-substituent R1 on the side chain benzene ring exhibited a tendency to increase the ratios of the tautomer A . 相似文献
42.
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
43.
Mao-Peng Lin Haeng-Boo Kim Tomiki Ikeda Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1992,30(11):2365-2369
Benzyl cation was detected by transient absorption spectroscopy with a spectroscopic multichannel analyzer on pulse excitation (fourth harmonic of Nd:YAG laser, 266 nm; 10 ns fwhm) of benzyl(4-hydroxyphenyl) methylsulfonium hexafluoroantimonate(BSS) in 1,2-dichloroethane (EDC). The benzyl cation was long-lived (lifetime, 59 ms) at room temperature and quenched by a vinyl ether compound. The formation of the benzyl cation as active species on photolysis of BSS is in contrast to the formation of Brønsted acids in other sulfonium salts so far reported. © 1992 John Wiley & Sons, Inc. 相似文献
44.
It has been shown by a series of experiments on 5-alkyl, 5-halo-, and other 5-substituted 1-naphthol derivatives that the product ratio of the ortho- and para-naphthoquinones formed on oxidation with Fremy's salt is controlled by the bulkiness of the C5-substituent. 相似文献
45.
Masao Ikeda Takashi Nakamura Yu Nagase Koji Ikeda Yoshiro Sekine 《Journal of polymer science. Part A, Polymer chemistry》1981,19(10):2595-2607
For the purpose of studying the mechanism of thermal degradation of poly[(tetramethyl-p-silphenylene) Siloxane] (poly TMPS) a series of polymers with silphenylene and siloxane bonds in the main chain were prepared and subjected to thermogravimetry (TG) and pyrolysis study. Analyses of products from poly TMPS degradation (in vacuum at a constant temperature) by gas chromatography (GC), infrared (IR), nuclear magnetic resonance (NMR) spectroscopy, and gas chromatography-mass spectrometry (GC–MS) revealed that degradation occurs at the silphenylene bonds. The TG curves obtained in He for heating rates of 1,2,2.5,7.5, and 10°C/min were analyzed by the Ozawa method; activation energies of 39 ± 1 and 45 ± 2 kcal/mol were obtained respectively for the initial cleavage of the methyl side group and the later-stage scission of the main-chain silphenylene bond which leads to a major weight loss. The results agree with those obtained for other structurally similar polymers. 相似文献
46.
T Oh-Hara Y Ikeda H Sakagami K Konno T Kaiya K Kohda Y Kawazoe 《Chemical & pharmaceutical bulletin》1990,38(1):282-284
We have found that water-soluble extracts of lignified natural products are strong potentiaters of hemolytic plaque-forming cell production in mice. Apparently, the active components involved belong to a lignin family. Consequently, study of medicinal potential, especially immunopotentiating capacity, of lignified materials is important. 相似文献
47.
New synthetic methods for the preparation of 1,3-dienes are described. 相似文献
48.
Porphyrin macrocycles composed of five and six units of m-gable imidazolylporphyrinatozinc (1-Zn) were synthesized by self-assembled cyclization followed by ring-closing metathesis linkings. Each porphyrin macrocycle was isolated by GPC chromatography, and their molecular weights were determined by MALDI-TOF mass spectroscopy. These structures represent mimics of light-harvesting complexes in photosynthetic bacteria. [structure: see text] 相似文献
49.
Charge-transfer interactions,exciplex formations and ionic dissociations in singlet oxygen reactions
Intermolecular perturbation and configuration interaction calculations have been carried out to elucidate the attacking modes of singlet molecular oxygen (1O2) to allyl olefins and electron-rich olefins, which are classified into four groups from their molecular structures. It is found: (1) that the attacking modes are dependent on the molecular structure of substrates ; (2) that the charge-transfer (CT) interactions between 1O2 and substrates are particularly important for the formation of exciplexes through which the ene and (2+2) reactions of 1O2 proceed ; and (3) that the CT energy levels are important in governing the fraction of ionic dissociation to produce Superoxide anion and the relative ratio between the (4+2) and (2+2) reactions of 1O2 with dienes, heterocycles and related species. 相似文献
50.
Shoichi Ikeda Gerald D. Fasman 《Journal of polymer science. Part A, Polymer chemistry》1970,8(4):991-1001
The absorption and fluorescence spectra of a detergent, polyoxyethylene octylphenyl ether, were measured in water at different concentrations. The absorption spectra had a peak at 275 mμ and a shoulder at 281 mμ. The spectra were independent of concentration below the critical micelle concentration, but the molar extinction coefficients of the peak and the shoulder increased with concentration above the critical micelle concentration. The critical micelle concentration value derived from the absorption data was in good agreement with those obtained by other methods. The fluorescence spectra of the detergent in water were independent of concentration in dilute solutions, if the intensities of the spectra were normalized at the peak at 302 mμ. At higher concentrations, a weak excimer band appeared at 345 mμ, whose intensity increased with concentration. The excimer band manifested itself at a concentration slightly lower than the critical micelle concentration. The main band decreased and the excimer band increased, as the temperature was raised. An excimer band was observed in the same region of the spectra for the pure detergent, either in the solid or liquid state. The equilibrium solid spectra exhibited a very strong excimer emission. It was concluded that the excimers were formed within micelles in the case of aqueous solutions. 相似文献