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151.
Tatsuro Ouchi Kazuo Hagita Hiroshi Sakamoto Minoru Imoto Tsutomu Iwamoto 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(12):1651-1665
Abstract The polymerization of some kinds of vinyl monomer was found to occur in aqueous solutions of poly(ethylene glycol) diglycolic acid (PEG Acid) or sodium poly(ethylene glycol) diglycolate (PEG Acid Na) through radical mechanisms without any further initiator, as a so-called “uncatalyzed polymerization.” Although the initiating radical species for PEG Acid was determined to be the same as that for PEG Acid Na by means of the spin-trapping technique, the initiating ability of PEG Acid was higher than that of PEG Acid Na. These results are assumed to be attributable to the difference in the initiation mechanisms of the two systems and in the incorporating abilities of monomer into the hydrophobic areas formed by PEG Acid and PEG Acid Na. 相似文献
152.
Reductive dehalogenation of aryl halides was achieved using hydrogen and a palladium catalyst. By using deuterium gas, the deuterated arenes were readily prepared. 相似文献
153.
Atsunori Morigaki Kazuki Tsukade Satoru Arimitsu Tsutomu Konno Toshio Kubota 《Tetrahedron》2013,69(5):1521-1525
The reaction of β-fluoroalkylated α,β-unsaturated ketones with various enamines gave 4-fluoroalkylated 3,4-dihydro-2H-pyrans as a major product in good yields by a one-pot operation, and these products display the high diastereoselection just after single recrystallization. This unexpected result is rationalized by the unique reactivity of β-fluoroalkylated α,β-unsaturated ketones. As the synthetic application, 4-trifluoromethyl tetrahydropyran was synthesized in moderate isolated yield with high diastereoselectivity. 相似文献
154.
In this paper, we report the preparation and red-light-emitting behavior of benzothiadiazole–tris(alkyloxy)phenylethene dyes. In solution, we observed an efficient red light emission with high fluorescence quantum yields (up to 0.78). With increase in solvent polarity, the emission bands shifted to longer wavelengths accompanied by a large Stokes shift of up to 152 nm. A moderate fluorescence quantum yield of 0.52 could be achieved even in the polar solvent dimethylformamide. Red light emission with good fluorescence quantum yields (up to 0.50) was also observed in the bulk solid, liquid, and film state. 相似文献
155.
Little is known of the biosynthesis of sesquarterpenes and the synthesis of unnatural terpenoids by sesquarterpene biosynthetic enzymes has not yet been reported. In this study, the enzymatic cyclization of head-to-tail acyclic triterpene β-hexaprene—a natural product isolated from Bacillus clausii—using tetraprenyl-β-curcumene cyclase (TC) from Bacillus subtilis resulted in the formation of two unnatural pentacyclic triterpenes. It was revealed that B. subtilis TC, which forms tetracyclic terpenoid scaffold from tetraprenyl-β-curcumene in vivo, could be used to construct the 6/6/6/6/6-fused pentacyclic scaffold in vitro, suggesting that the active site cavity of TC has sufficient space to accommodate this unnatural pentacyclic scaffold. This is the first report demonstrating the utility of a sesquarterpene cyclase toward the synthesis of unnatural terpenoids. 相似文献
156.
157.
Kiyofumi Katagiri Keiko Ohta Kunihito Koumoto Kei Kurosu Yoshihiro Sasaki Kazunari Akiyoshi 《Colloid and polymer science》2013,291(6):1375-1380
Novel organic–inorganic hybrid nanoparticles consisting of polymer–hydrogel nanoparticles (nanogels) and iron oxide were developed for potential biomedical applications. Hybrid nanoparticles were prepared by a simple procedure using polysaccharide nanogels as a reactive site for iron oxide formation. The hybrid nanoparticles have a narrow size distribution with a diameter of approximately 30 nm and show high colloidal stability. These nanohybrid particles could be used as a contrast medium for magnetic resonance imaging or for magnetic hyperthermia therapy. 相似文献
158.
Masami Sakamoto Kazuya Yoshiwara Fumitoshi Yagishita Wataru Yoshida Takashi Mino Tsutomu Fujita 《Research on Chemical Intermediates》2013,39(1):385-395
The irradiation of methyl 2- and 3-chromonecarboxylate in the presence of various alkenes afforded cyclobutane type adducts, whose structures were established by X-ray structural analysis. Methyl 2-chromonecarboxylate showed higher photochemical reactivity than methyl 3-chromonecarboxylate, in which endo adducts were yielded as major products. 相似文献
159.
Dr. Kazukuni Tahara Yuki Yamamoto Dr. Dustin E. Gross Hiroyoshi Kozuma Yoko Arikuma Dr. Koji Ohta Dr. Yoshiko Koizumi Yuan Gao Dr. Yo Shimizu Prof. Shu Seki Dr. Kenji Kamada Prof. Jeffrey S. Moore Prof. Yoshito Tobe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(34):11251-11260
We present herein the synthesis and properties of the largest hitherto unknown graphyne fragment, namely trigonally expanded tetrakis(dehydrobenzo[12]annulene)s (tetrakis‐DBAs). Intramolecular three‐fold alkyne metathesis reactions of hexakis(arylethynyl)DBAs 9 a and 9 b using Fürstner’s Mo catalyst furnished tetrakis‐DBAs 8 a and 8 b substituted with tert‐butyl or branched alkyl ester groups in moderate and fair yields, respectively, demonstrating that the metathesis reaction of this protocol is a powerful tool for the construction of graphyne fragment backbones. For comparison, hexakis(arylethynyl)DBAs 9 c – g have also been prepared. The one‐photon absorption spectrum of tetrakis‐DBA 8 a bearing tert‐butyl groups revealed a remarkable bathochromic shift of the absorption cut‐off (λcutoff) compared with those of previously reported graphyne fragments due to extended π‐conjugation. Moreover, in the two‐photon absorption spectrum, 8 a showed a large cross‐section for a pure hydrocarbon because of the planar para‐phenylene‐ethynylene conjugation pathways. Hexakis(arylethynyl)‐DBAs 9 c – e and 9 g and tetrakis‐DBA 8 b bearing electron‐withdrawing groups aggregated in chloroform solutions. Comparison between the free energies of 9 e and 8 b bearing the same substituents revealed the more favorable association of the latter due to stronger π–π interactions between the extended π‐cores. Polarized optical microscopy observations, DSC, and XRD measurements showed that 8 b and 9 e with branched alkyl ester groups displayed columnar rectangular mesophases. By the time‐resolved microwave conductivity method, the columnar rectangular phase of 8 b was shown to exhibit a moderate charge‐carrier mobility of 0.12 cm2 V?1 s?1. These results indicate that large graphyne fragments can serve as good organic semiconductors. 相似文献
160.
Co–Pd bimetallic alloy nanoparticle catalysts were prepared from CoCl2, Pd(OAc)2 and several capping agents with Li(C2H5)3BH. The nanoparticle catalysts were applied to the aerobic oxidation of a variety of alcohols in water to give the corresponding carbonyl products. The catalyst was magnetically recovered and reused for further oxidation. The nanoparticle catalysts were characterized with TEM, ICP, and XPS analyses. 相似文献