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71.
trans-Stilbene, 1, 1-diphenylethylene, and α-methylstyrene were allowed to react with dibenzylmagnesium to form their oligomers in hexamethylphosphortriamide (HMPA). One and two molecules of stilbene and 1, 1-diphenylethylene were incorporated into the magnesium carbon bond, and the carbanions obtained in HMPA were stable in analogy with the anionic living polymer having alkali cation as the gegenion in eithers. Intense coloration was observed during the reaction between α-methylstyrene and dibenzylmagnesium as well as in the case of stilbene and 1, 1-diphenylethylene. The low molecular weight products which were formed after a long time in the reaction between α-methylstyrene and dibenzylmagnesium were found to have no magnesium-carbon bond. It was considered that the cleavage of the propagating chain occurred gradually after the rapid propagation had proceeded to consume the monomer. 相似文献
72.
Yasuhiro Matoba Hiroshi Inoue Jun-Ichi Akagi Takuji Okabayashi Yasutaka Ishii Masaya Ogawa 《合成通讯》2013,43(9):865-873
Applicatims a Mo- and W-based heteropoly acids (HPA) as a catalyst in the oxidation of olefins have extensively been investigated1. However, a patent work is only attempted concerning the evoxidatim of olefins with H202 by HPA2) since the oxirane ring is cleaved because of a strong acidity of HPA itself. Herein, an effective epoxidatim of some allylic alcohols with H202 by a new Mo-species (MPCP), which was prepared from 12-molybdatophosphoric acid (H3PMo12040) and cetylpyridinium chloride (C5H5N (CH2), 15CH3- C1-) under two-phase conditions using chloroform as an organic solvent, is described. 相似文献
73.
Seiichi Ohta Susumu Inasawa Yukio Yamaguchi 《Journal of Polymer Science.Polymer Physics》2012,50(12):863-869
When a mixture of liquid crystal (LC) and photo reactive monomer is irradiated by UV light, polymerization occurs and LC droplets form through phase separation, producing polymer dispersed LCs (PDLCs). Although size control of LC droplets and reduced amounts of LC in PDLC films are important in applications, precise size control of LC droplets at a low LC fraction has not yet been accomplished. In this study, the phase diagrams of the LC/initial monomer and the LC/polymer during polymerization were used to control LC droplet size at various LC fractions. Both the relative position of the sample in the initial phase diagram and the shift of the phase separation line during polymerization were shown to be important in determining the size of LC droplets. Our results are expected to provide a new strategy for precise size control of LC droplets especially at a low LC fraction range, which would be a great help for PDLC applications. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献
74.
75.
In laser frequency scanning interferometry for measurements of absolute lengths, a small drift in the measured length during the frequency scan yields an enlarged offset error in the measured result. Although such an error is unavoidable for an on-site interferometric system, methods for solving this problem have not been developed. We propose a frequency scanning interferometric system immune to the dynamic length change employing a pair of vertical-cavity surface-emitting laser diodes whose frequencies are equally scanned in opposite directions. The offset error is canceled by averaging the two phase shifts of the interferograms obtained from the light sources. 相似文献
76.
A measurement technique for depth profiling in a time-domain low-coherence interferometer has been proposed. The spatial variation
of the optical path caused by a diffraction grating in the Littrow configuration produces a white-light interferogram. A one-dimensional
charge-coupled device (1D-CCD) detector is used to measure the undersampled white-light interferogram. The position of the
reflective boundary is calculated from the rate of phase change with spatial frequency, which is based on the sub-Nyquist
sampling of the white-light interferogram in the frequency domain. 相似文献
77.
78.
The acceleration effect of poly(ethylene oxide) on nucleophilic reactions was investigated. The enhancement of the reaction rate was interpreted by the cooperative solvation of alkali metal ions with ethereal oxygens of PEO resulting in active nucleophilic anions. In relation to the complex formation of alkali metal ions with PEO, the oligo(ethylene oxide) derivatives were prepared as the synthetic ionophores, which were able to transport alkali metal ions selectively through a liquid membrane against the alkali metal ion concentration. 相似文献
79.
Syntheses of cyclic oligomer and polymer were attempted with magnesiacyclohexane as the initiator in HMPA. The oligomer of α-methylstyrene, initiated by magnesiacyclohexane, was treated with dimethyldichlorosilane in order to obtain a stable cyclic oligomer. The products were investigated by GPC, IR, NMR, and elemental analysis. It was found that magnesia-cyclohexane could not be activated enough by HMPA, and that the magnesium-carbon bond was not stable in HMPA, and that the chain transfer reaction might occur repeatedly during the polymerization. Consequently, the yield of cyclic oligomer was so low that cyclic compounds could not be discriminated from the linear oligomer. 相似文献
80.
Molydbenum and tungsten-catalyzed oxidations of alcohols with dilute hydrogen peroxide under phase-transfer conditions have been focused in recent years 1–3. In a previous paper, we have reported that tricetylpyridinium-12-molybdophosphate(CMP), [π - C5H5N+(CH2 15CH3]3 (PMO12O40)3-, prepared from 12-molybdophosphoric acid (MPA) and cetylpyridinium chloride (CPC), catalyzed the oxidation of secondary alcohols to carbonyl compounds with tert-butylhydroperoxide(t-BuOOH)4. When hydrogen peroxide in place of t-BuOOH was employed as the oxidant for the above oxidation, however, alcohols were oxidized with difficulty to give carbonyl compounds in poor yields. In continuation of this study, we wish to report here the selective oxidation of secondary hydroxy group of alcohols and diols and diols with H2O2 under the influence to tricetylpyridinium-12 tungstophosphate (CWP), [π-C5H5N+ (CH2) 15 CH3]3(PW12O40)3-, derived from 12-tungstophosporic acid (WPA) and CPC. 相似文献