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141.
Taisei Ueda Naoyoshi Yatsuzuka Shin‐Ichi Nagai Kumiko Okada Emi Takeichi Hiromi Segi Jinsaku Sakakibara 《Journal of heterocyclic chemistry》2001,38(1):141-145
Oxidation of 7,8‐diaminotheophylline (1) with lead tetraacetate in refluxing toluene gave a mixture of 3‐amino‐5,7‐dimethylpyrimido[4,5‐e][1,2,4]triazine‐6,8‐dione ( 2 ) and 6‐cyanoimino‐5‐diazo‐1,3‐dimethylpyrimidine‐2,4‐dione ( 4 ). The latter was transformed to 2 by the reaction with 1‐propanethiol in quantitative yield. The reaction of 4 with methanol, ethanol and 1‐propanol in the presence of rhodium ( II ) acetate gave 5‐alkoxy‐6‐(2‐alkyl‐3‐isoureido)‐1,3‐dimethylpyrimidine‐2,4‐diones ( 7a‐c ). A similar reaction of 4 with alkylamines such as n‐propylamine, n‐butylamine, isobutylamine and n‐hexylamine gave a mixture of 7‐alkyl‐8‐aminotheophyllines ( 8a‐d ) and (5‐alkylamino‐1,3‐dimethyl‐2,4‐dioxopyrimidin‐6‐yl)cyanamides ( 9a‐d ). 相似文献
142.
Takumi Watanabe Yuji Tsunoda Akira Matsuo Kenji Sugiyama Akira Hirao 《Macromolecular Symposia》2006,240(1):23-30
A series of dendrimer-like star-branched poly(methyl methacrylate)s (PMMA)s of generations consisting of four branched segments at each junction have been successfully synthesized by developing an iterative methodology. It involves two reaction steps in each iterative reaction sequence, (a) a coupling reaction of the α-functionalized living anionic PMMA with four tert-butyldimethylsilyloxymethylphenyl (SMP) groups with benzy bromide (BnBr)-chain-functionalized PMMA and (b) a transformation of SMP group into BnBr functionality. By repeating the reaction sequence thrice, the above-mentioned dendrimer-like star-branched (PMMA)s of up to third-generation made up of 4, 20, and 84 PMMA segments and 16, 64, and 256 BnBr termini were synthesized by the first, second, and third iterative processes, respectively. The resulting polymers all were well-defined in branched architecture and precisely controlled in chain length. 相似文献
143.
Keita Sakakibara Yasuhiro Ogawa Fumiaki Nakatsubo 《Macromolecular rapid communications》2007,28(11):1270-1275
Langmuir‐Blodgett films of a cellulose derivative containing porphyrins, porphyrin‐cellulose, were fabricated in order to construct a cellulose‐based molecular photocurrent generation system. On visible light illumination of the LB monolayer film deposited on an ITO electrode, anodic photocurrents were observed with a quantum yield of 1.6% at an applied potential of 0 V versus SCE, and 3.8–4.6% at 0.2–0.3 V versus SCE. These values indicate that the self‐quenching of the photoexcited porphyrins in the cellulose LB film was suppressed, while porphyrin moieties in the LB film had a densely packed structure. This is because the porphyrins are located at a distance of approximately 1.0 nm along the cellulose backbone.
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Kinetic study of the reactions of diphenyldiazomethane with various electron acceptors were made in six aromatic solvents. Log k were correlated with the solvent basicity parameter, Dπ, and the regression slopes were found to be a function of electron affinities. 相似文献
146.
Haruyasu Asahara Takuya Koizumi Eiko Mochizuki Takumi Oshima 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(3):o136-o138
The crystal structures of the two thermally equilibrated conformational isomers of the epoxide 1′,5′‐dimethylspiro[10,11‐dihydro‐5H‐dibenzo[a,d]cycloheptene‐5,8′‐4′‐oxatricyclo[5.1.0.03,5]octane]‐2′,6′‐dione, C23H20O3, have been determined by X‐ray diffraction. In the tricyclic dione skeleton, the oxirane and cyclopropane rings adopt an anti structure with respect to the conjunct quinone frame. The spiro‐linked 10,11‐dihydro‐5H‐dibenzo[a,d]cycloheptene ring of the major isomer has a fairly twisted boat form, folding opposite to the adjoining cyclopropane methyl substituent, whereas the seven‐membered ring of the minor isomer has an almost ideal twist–boat form, inversely folding to the side of the relevant methyl group. The conformational structures of these isomers have been compared with those of the corresponding isomers of the unepoxidized homobenzoquinone. 相似文献
147.
Mohammed Omar Keng Chuah Kozo Saito Akira Numasato Masahito Sakakibara 《Infrared Physics & Technology》2006,48(3):240-248
This paper describes a newly-developed automated thermal system for detection of seeds on newly painted car shells. The system’s novel approach is to use thermal emission; previously applied techniques relied on light reflection strategies. The system is described beginning with analytical modeling of the underlying detection theory to verification on a pilot run in an automotive production line. Parker’s flash procedure, using a thermal detector, was performed to extract the thermal properties of inspected panels. New computer logic developed in-house for processing the acquired thermograms is also presented. 相似文献
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