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51.
Kosuke Katagiri Yukina Yamamoto Yuui Takahata Ryoga Kishibe Naoki Fujimoto 《Tetrahedron letters》2019,60(30):2026-2029
Anthracenyl(diphenyl)phosphine oxide and dianthracenylphenylphosphine oxide as photoactive compounds have been synthesized. Anthracenyl group of these compounds indicate the multi-functional roles such as an emission component, a photodimerization component, and a leaving group. When the light irradiation was performed under an oxygen atmosphere, photo-oxidative PC bond cleavage to leave the antharacenyl group was observed. Moreover, phosphonyl radical was produced and then PP bond formation to form diphosphane was observed. 相似文献
52.
Katsuma Hiraki Shigeru Ikeda Shoichi Kaneko Hidefumi Hirai 《Journal of polymer science. Part A, Polymer chemistry》1979,17(8):2363-2369
n-Butyl titanate(IV)–triethylaluminum catalyst at Al/Ti molar ratios greater than 6 polymerizes methyl and n-butyl acrylates at ?78°C. The polymerization system which includes methyl acrylate at ?78°C, gives two ESR signals with g factors of 1.958 and 1.961 that overlap each other. The absorption intensity of the latter signal is approximately proportional to the polymer chain concentration calculated from polymer yield and the molecular weight. The polymerization system at Al/Ti ratios smaller than 3 has no catalytic activity on the polymerization and shows only the ESR signal with the g factor of 1.958. On the basis of these facts the ESR signal with the g factor of 1.961 is attributed to the active growing end of poly(methyl acrylate) with this catalyst. The character of this active growing end is discussed. 相似文献
53.
Fischer indolization of ethyl pyruvate 2-methoxyphenylhydrazone (1) with p-toluene-sulfonic acid in benzene in the presence of an enolizable dicarbonyl or an indolic compound gave either an indole product having an active methine group at C6 or a novel type of 3,6′-biindole compound. Structures of the products were established by NMR spectra and chemical evidence. 相似文献
54.
Hasegawa E Takizawa S Iwaya K Kurokawa M Chiba N Yamamichi K 《Chemical communications (Cambridge, England)》2002,(17):1966-1967
Photoinduced electron transfer reaction of 2-bromomethyl-2-(3-butenyl)benzocyclic-1-alkanones with amines afforded 5-exo radical cyclization products while electron transfer reaction with samarium diiodide produced cyclopropanols. 相似文献
55.
A new optical CO2 sensor based on the luminescence intensity change of the europium(III) complex tris(thenoyltrifluoroacetonato) europium(III) dihydrate ([Eu(tta)3]) caused by the absorption change of various pH indicators—thymol blue, phenol red, or cresol red—with CO2 was developed and its CO2 sensing properties were investigated. For all the CO2 sensors using pH indicators the observed luminescence intensity from [Eu(tta)3] at 613 nm increased with increasing CO2 concentration. The linear calibration method based on the plot of (I100–I0)/(I–I0) versus the inverse of CO2 concentration was suggested, where I0 and I100 were luminescence intensities at 613 nm of the CO2 sensor film in 100% nitrogen and 100% gaseous CO2. In all cases the plots showed good linearity and the correlation factors of the plots, r2, were 0.991 for thymol blue, 0.990 for phenol red, and 0.998 for cresol red. The slopes of the plots (A/B) for thymol blue, phenol red, and cresol red were 2.2, 5.2, and 9.0%, respectively. The response times of the CO2 sensor film were 4.0 s for thymol blue, 4.4 s for phenol red, and 8.8 s for cresol red for switching from nitrogen to CO2, and the recovery times of films were 36 s for thymol blue, 39.2 s for phenol red, and 56.6 s for cresol red for switching from CO2 to nitrogen. The signal changes were fully reversible and hysteresis was not observed during the measurements. The highly sensitive CO2 sensor was developed using thymol blue as an indicator for the CO2-sensing probe. 相似文献
56.
Naoki KakusawaYoshinori Tobiyasu Shuji YasuikeKentaro Yamaguchi Hiroko SekiJyoji Kurita 《Tetrahedron letters》2003,44(47):8589-8592
The reaction of 12-arylethynyl-6-methyl-5,6,7,12-tetrahydrodibenzo[c,f][1,5]-azastibocines with organic halides such as acyl halides and aryl halides in the presence of PdCl2(PPh3)2 as a catalyst led to the formation of cross-coupling products, alkynyl ketones and diaryl acetylenes, in good yields. The reactivity of the ethynyl group on the 1,5-azastibocines was far superior to that on diphenyl(phenylethynyl)stibane, which brought about marked improvement in the reaction conditions (lower temperature and shorter reaction time) and in the yields of the cross-coupling products. Single-crystal X-ray analysis of the ethynyl-1,5-azastibocine showed the presence of intramolecular Sb?N interaction which should be responsible for the remarkable reactivity enhancement of the 1,5-azastibocines for this type of reaction. 相似文献
57.
Osamu Sangen Singo Masuda Hidehiko Nakano Kazusige Yamana Kenichi Sasaki Naoki Ikeda 《Journal of polymer science. Part A, Polymer chemistry》1992,30(6):1171-1175
A new synthetic pathway of A–B–A tri-block copolyether which is composed of a hydrophilic poly(oxyethylene) unit as an A part and a hydrophobic poly(oxy-2-methyl-trimethylene) unit as a B part is proposed. Telechelic α-tosyl-ω-tosyloxypoly(oxy-2-methyl-trimethylene) derived from tosylation of poly(oxy-2-methyl-trimethylene glycol) (PMTG) was allowed to react with poly(ethylene glycol) (PEG) in the presence of sodium hydroxide. Tg of the resulting A–B–A tri-block copolyether (PEMG) (M?n = 1600) was ?72°C and its specific gravity [D415] was 1.055. 相似文献
58.
Some water-soluble organic iodine compounds (aqueous solution) can be analyzed for iodine by isotopically exchanging with labelled elementary iodine (organic solution). The method is applicable to exchange systems in which the rate of the exchange is rather small but measurable, before the exchange equilibrium is attained. The iodine content of iodoaromatic amino acids such as 5-iodouracil and 3,5-diiodotyrosine can be determined within an error of ±4%. 相似文献
59.
Toru Takagishi Naoki Matsui 《Journal of polymer science. Part A, Polymer chemistry》1987,25(9):2511-2520
The extent of binding of chrome violet, which is a monoazo dye and involves two hydroxyl groups in o and o′ positions to azo group, by polyvinylpyrrolidone is markedly enhanced in the presence of Co2+ ion. The amount of binding in the presence of 1 × 10?4 mol/L of Co2+ ion increases by a factor of about 10 compared to that in the absence of the metal ion. Ni2+ and Zn2+ ions do not perceptively influence the binding affinity of the dye. Cu2+ ion, in contrast, suppresses the binding. To investigate further the action of added metal ions, a cobalt–complex dye was prepared and its binding property for the polymer was compared to that of chrome violet in the presence of metal ions. Some possible mechanisms for the enhancement of chrome violet binding by the addition of Co2+ ion are described. 相似文献
60.
A continuous-flow hydride generator is modified and miniaturized for the determination of picogram amounts of arsenic by atomic absorption spectrometry. A 300-μl sample is dropped into a teflon cup and pumped into an alkaline sodium tetrahydroborate stream, which is acidified in a reaction coil. The evolved hydride is swept with argon through a phase separator into an electrically-heated quartz absorption cell and the absorbance is recorded. To eliminate differences in sensitivity between arsenic(III) and arsenic(V) without prereduction by potassium iodide, it is important that arsenic(V) be mixed with tetrahydroborate prior to mixing with hydrochloric acid. The method has a detection limit of 0.08 ng As ml?1 (24 pg) and the calibrations is linear up to 50 ng As ml?1. The relative standard deviation for 10 replicate measurements is 5.4% for 0.5 ng As ml?1. The addition of potassium iodide and hydroxylamine is confirmed to be effective in minimizing some interferences. The sampling rate is 90 h?1. Results for NBS biological and steel reference materials demonstrate applicability of the technique. 相似文献