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191.
The chiral selector L -t-leucine-t-butylamide has been anchored to a polysiloxane by nucleophilic displacement of 2,2,2-trifluoroethyl ester-functionalized block polysiloxanes with L -t-leucine-t-butylamide. Attempts were made to immobilize the chiral polysiloxanes inside the capillaries by thermal treatment at 300°C for 30–90 min. The polysiloxanes were found to be more resistant than Chirasil-Val to the racemization caused by such high temperature treatment. Capillary columns coated with this type of immobilized polysiloxane have shown very high enantioselectivity and thermal stability. 相似文献
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T. Ohta T. Yokoyama S. Terada A. Imanishi Y. Kitajima 《Research on Chemical Intermediates》2000,26(1):29-43
Adsorption and surface chemical reactions of SO2 on Ni, Cu and Pd metal surfaces are studied by using surface XAFS, as well as XPS and STM. It has turned out that SO2 lies flat on the Ni(100), Ni(110) and Ni(111) surfaces, while it stands on Pd(100) and Pd(111). By raising the temperature,
surface reactions occur on these metal surfaces. Typical reactions on Ni and Cu are 3SO2 → S+2SO3, while those on Pd are 2SO2 → S+SO4. The structures of the adsorbate species are elucidated. 相似文献
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Etsuo Yonemochi Naho Furuyama Mika Bunko Taro Moriwaki Yuka Ikemoto Katsuhide Terada 《Infrared Physics & Technology》2008,51(5):450-453
Troglitazone exists as four isomers in equal amount and these isomers compose two racemic compounds, RR/SS and RS/SR. The objective of this study was to discriminate between the racemic compounds and between the crystal and amorphous forms of troglitazone in solid dispersions (SDs) using IR-to-THz imaging. SDs of troglitazone with polyvinylpyrrolidone (PVP, carrier) were prepared by the closed melting method. SDs were heated at various temperatures and water content. The mid-to-far infrared measurements for the powder samples were performed by using the synchrotron radiation source at the BL43IR in SPring-8. Crystalline RR/SS (L) and RS/SR (H) showed different spectra, that is, each form had a specific peak, respectively. However, amorphous forms prepared from each crystalline form exhibited the same spectra. Using the chemo-metric analysis, the existing component was decided in each pixel and the distribution of crystalline L, H and amorphous troglitazone in SDs could be illustrated. For the sample heated at 105 °C, 75%RH, scattered plots of H and amorphous against PVP showed the trend for H was negative; on the other hand, amorphous showed positive correlation. This result suggested that H existed separately, whereas amorphous would be dissolved in PVP. Based on these evaluations, it was clear that the physical state and distribution of troglitazone in SDs, including the discrimination between L, H, and amorphous, reflect the preparation conditions. Chemical imaging can observe a difference in the dispersed state of drug and ingredient in a visible image by performing statistical processing. 相似文献
199.
Nakanishi I Nishizawa C Ohkubo K Takeshita K Suzuki KT Ozawa T Hecht SM Tanno M Sueyoshi S Miyata N Okuda H Fukuzumi S Ikota N Fukuhara K 《Organic & biomolecular chemistry》2005,3(18):3263-3265
Photoreduction of pyridine N-oxide, which has a key structure of antitumor agents for hypoxic solid tumors, by 1-benzyl-1,4-dihydronicotinamide in deaerated aprotic media resulted in generation of hydroxyl radical, leading to the oxidation of salicylic acid to 2,3- and 2,5-dihydroxybenzoic acids, and catechol. 相似文献
200.