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41.
The title compound a novel cyclophane containing p-tropoquinone, was synthesized starting from 5-methoxytropolone and its physical properties were discussed comparing with those of 3,7-dimethyl-p-tropoquinone and p-benzoquinonophane. The reduced quinone character exhibited by was ascribed to the intramolecular CT interaction and the deformation of the quinone ring. 相似文献
42.
Yoshiki Chujo Kenji Kohno Noriyuki Usami Yuya Yamashita 《Journal of polymer science. Part A, Polymer chemistry》1989,27(6):1883-1890
Amphiphilic block copolymers, i.e., poly(methyl methacrylate)-b-poly(2-dimethylethylammoniumethyl methacrylate), were synthesized by the reaction between two prepolymers. Carboxyl-terminated poly(methyl methacrylate) and hydroxyl-terminated poly(2-dimethylaminoethyl methacrylate) were prepared by radical polymerization of the corresponding monomers in the presence of thioglycolic acid and 2-mercaptoethanol as a chain transfer agent, respectively. Two condensation methods, i.e., DCC and the acid chloride method, were used for the reactions of these prepolymers. The subsequent quarternization produced the amphiphilic block copolymers. Surface property of poly(methyl methacrylate) films containing this amphiphilic block copolymer was examined by measuring contact angles for water. The addition of only 0.5 wt% of the block copolymer was sufficient to make poly(methyl methacrylate) surfaces hydrophilic. The block copolymer formed a polymeric micelle in acetone–water mixed solvent. 相似文献
43.
Mitsuru Ueda Akira Sato Yoshio Imai 《Journal of polymer science. Part A, Polymer chemistry》1979,17(3):783-787
Catalytic actions of various additives were studied in the polycondensation of di(4-nitrophenyl) isophthalate with bis(4-aminophenyl) ether in N-methyl-2-pyrrolidone, and 1-hydroxybenzotriazole (HOBt) was found to be a highly effective catalyst that yielded high-molecular-weight polyamide. In addition to the polycondensation of the 4-nitrophenyl ester, the polymerization of negatively substituted phenyl esters like di(2,4,5-trichlorophenyl) isophthalate was also accelerated by HOBt. For the HOBt-catalyzed aminolysis of esters a bifunctional concerted mechanism that involves an eight-membered transition state was proposed. 相似文献
44.
Bromomagnesium ureide-carbon dioxide adducts, models of the carboxylated biotin complex, undergo caboxylation of a variety of carbonyl compounds in good yield. 相似文献
45.
We developed a novel measurement method of the Donnan potential difference at a charged membrane/salt solution interface. The method can measure the potential under the condition that the membrane charge density is much lower than the KCl concentration of the salt bridge. This method is very useful for obtaining the effective charge density of each layer of a bipolar membrane. The present experiments in a system of a negatively charged poly(vinyl alcohol) membrane and a single salt solution of KCl, NaCl, LiCl, CaCl2 and LaC3 revealed that the membrane effective charged density has the same value for all the ions. The experiments in mixed KCl and CaCl2 solution revealed that the potential in the system is governed mainly by the concentration of the counterion having the highest valence in the system. 相似文献
46.
Shuntaro Mataka Akira Hosoki Kazufumi Takahashi Masashi Tashiro 《Journal of heterocyclic chemistry》1980,17(8):1681-1685
The reaction of tetrasulfur tetranitride ( 1 ) with various aryl and alkyl benzyl ketones ( 2a-o ), oxindole ( 11 ), benzyl α-pyridyl ketone ( 12 ) and α-phenacylpyridine ( 13 ) afforded the corresponding 1,2,5-thiadiazoles ( 3a-n, 11 and 14 ). The scope and limitations of the above reaction were investigated and the evidences suggesting the radical anion mechanism are presented. 相似文献
47.
The basic primary and scatter dose-spread kernels used for convolution methods are usually produced by Monte Carlo simulations with the interaction point forced to the center of a large water phantom. However, it is still not clear whether such Monte Carlo based kernels allow accurate dose calculations with a wide range of field sizes and depths, especially in thorax phantoms. Using the differential primary and scatter concept, this paper proposes another type of basic kernel, with which perfectly accurate primary and scatter absorbed dose calculations can be performed under conditions that the beam is parallel, the incident beam intensity is uniform within and zero outside the field, and the primary beam attenuation coefficient along raylines is not a function of depth and off-axis distance. 相似文献
48.
Yoshimasa Fukazawa Satoshi Harada Akira Inai Toshiya Okajima 《Tetrahedron letters》1993,34(52):8493-8496
The title compound (2) has been synthesized, the structure and the physical properties of which are investigated by X-ray, spectroscopic analyses, and MO calculations. There exists charge transfer (CT) interaction between the tropylium ion and the facing phenyl ring. From the pKR+ value of 2, it can be clear that the cation 2 is stabilized by the CT interaction. In spite of the presence of bond weakening σ-π orbital mixing, the cation 2 withstands retro[4+4]type bond cleavage, which is quite interesting when compared to a facile cleavage for the congener with anthracene photodimer type structure. 相似文献
49.
Akira Matsumoto Hisako Mano Masayoshi Oiwa George B. Butler 《Journal of polymer science. Part A, Polymer chemistry》1989,27(6):1811-1816
The radical polymerization of tetraallyl ammonium chloride (TAAC) was carried out in water using azo-initiator as compared to that of diallyl dimethyl ammonium chloride (DADMAC); the rate of polymerization was quite low for TAAC, around one-third of DADMAC. Kinetic discussion revealed the importance of degradative chain transfer in the polymerization of TAAC. The cyclopolymerizability of TAAC was estimated kinetically as the ability of 5-membered monocyclic radical to form a bicyclic ring, giving the cyclization constant of 21 mol/L at [M] = 2 mol/L. Gelation occurred at around 20% conversion. 相似文献
50.
Tetsuji Ohata Etsuro Fukumori Akira Matsumoto Masayoshi Oiwa 《Journal of polymer science. Part A, Polymer chemistry》1980,18(3):1011-1019
The radical copolymerization of diallyl tartrate (DATa) (M1) with diallyl succinate (DASu), diallyl phthalate (DAP), allyl benzoate (ABz), vinyl acetate (VAc), or styrene (St) was investigated in order to disclose in more detail the characteristic hydroxyl group's effect observed in the homopolymerization of DATa. In the copolymerization with DASu or DAP as a typical diallyldicarboxylate, the dependence of the rate of copolymerization on monomer composition was different for different copolymerization systems and unusual values larger than unity for the product of monomer reactivity ratios, r1r2, were obtained. In the copolymerization with ABz or VAc (M2), the r1 and r2 values were estimated to be 1.50 and 0.64 for the DATa/ABz system and 0.76 and 2.34 for the DATa/VAc system, respectively; the product r1r2 for the latter copolymerization system was found again to be larger than unity. In the copolymerization with St, the largest effect due to DATa monomer of high polarity was observed. Solvent effects were tentatively examined to improve the copolymerizability of DATa. These results are discussed in terms of hydrogen-bonding ability of DATa. 相似文献