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11.
介绍催化光度法测定锰的分析方法,讨论各显色体系中的灵敏度、测定范围和干扰情况,比较了测定锰的显色剂。引用文献58篇。 相似文献
12.
Tadatomi Nishikubo Atsushi Kameyama Jun Yamashita Masao Tomoi Wakichi Fukuda 《Journal of polymer science. Part A, Polymer chemistry》1993,31(4):939-947
The addition reaction of oxiranes ( 26a—e ) with carbon dioxide (CO2) was performed using insoluble polystyrene beads containing pendant quaternary ammonium or phosphonium salts as catalysts under atmospheric pressure. The reaction of 26a—e with CO2 proceeded smoothly catalyzed by 1–2 mol % of the polymer-supported quaternary onium salts to give the corresponding cyclic carbonates ( 27a—e ) in high yields at 80–90°C. In this reaction system, the catalytic activity of the polymer-supported quaternary onium salts was strongly affected by the following factors: degree of ring substitution (DRS) of the onium salt residues to the polymer, degree of crosslinking (DC) of the polystyrene beads, chain length of the alkylene spacer between the polymer back-bone and the onium salt, hydrophobicity of the alkyl group on the onium salts, and kind of onium salts. That is, the polymer-supported quaternary phosphonium salts with low DRS and DC and with long alkylene spacer chain were found to have higher catalytic activity than low molecualr weight quaternary onium salts. The above polymer-supported catalysts can easily be separated at the end of a reaction by filtration and can be reused for at least seven runs. It was also found that the rate of reaction was proportional to the products of catalyst concentration and oxirane concentration. © 1993 John Wiley & Sons, Inc. 相似文献
13.
Yoshitaka Gotoh Yutaka Kohno Wakichi Fukuda Masao Tomoi 《Journal of polymer science. Part A, Polymer chemistry》1994,32(8):1543-1550
Soluble polystyrenes with crown ether structures and hydroxyl groups adjacent to the macrorings were prepared by the reaction of epoxide-containing polystyrenes with monoaza-15-crown-5 or monoaza-18-crown-6. Rate of formation of the polymer-bound alkali cation-crown alkoxide ion pair from the soluble polystyrenes and aqueous NaOH or KOH depended on the loading of crown ether and hydroxyl units and on the size of the macroring. The elimination of HCl from less reactive 2-chloroethylbenzene with aqueous NaOH or KOH in the presence of the soluble polystyrene catalysts under two-phase conditions was limited mainly by the intrinsic reaction rate. The elimination of HBr from more reactive 2-bromoethylbenzene in the presence of the less (11%) ring-substituted polymer catalyst with 18-crown unit was limited by the alkoxide formation rate. © 1994 John Wiley & Sons, Inc. 相似文献
14.
JieLiang Bi-qianLiu 《高分子科学》2005,(1):83-92
Plasma-induced surface graft copolymerization of acrylic acid on polypropylene non-woven fabric (PP-g-AA) and polypropylene membrane were reported. The extents of grafting were controlled by the plasma and polymerization condition. Hexadecyltrimethyl ammonium bromide was then coupled with the carboxyl group of PP-g-AA to obtain a polyion complex (PIC). At last, CF4 plasma was used to give PICs hydrophobic property. The moisture regain and water-repellency of the processed PICs was investigated. The surfaces were characterized using ATR FT-IR and XPS. The result indicates that the products have very high ability to adsorb moisture, even better than cotton fiber. At the same time, the products show excellent hydrophobic property, which can‘t be wetted by those reagents whose surface tensions were higher than 327mN/m. 相似文献
15.
Natalia N. Sergeeva 《Tetrahedron》2007,63(50):12454-12464
Hydroporphyrins have been synthesized using both Pd-catalyzed and non-catalyzed approaches. Comparative studies of the reaction of tetrasubstituted porphyrins with organolithium reagents in the presence of and without palladium catalysts showed that depending on reagents, the catalyst structure and reactivity of the corresponding porphyrins, chlorins (β-hydroporphyrins) and/or porphodimethenes (meso hydroporphyrins) of 5,10-type can be prepared in reasonable yields. In the absence of Pd catalysts, the formation of chlorins is predominant in the reactions with aliphatic RLi while porphodimethenes are the main products in reactions with PhLi. The use of a palladium catalyst resulted in the formation of both types of hydroporphyrins and the selective formation of either β-mono- or disubstituted chlorins. Of special interest was the reaction of octaethylporphyrin. Here, reaction with t-BuLi in the presence of Pd(PPh3)4/CuI proceeded with complete regioselectivity for 5,10-porphodimethenes. 相似文献
16.
A novel chemiluminescence (CL) sensor for isoniazid combined with flow-injection technology is presented in this paper. The analytical reagents, luminol and ferricyanide, were both immobilized on an anion-exchange column. The CL signal produced by the reaction between luminol and ferricyanide, which were eluted from the column through sodium phosphate injection, was decreased in the presence of isoniazid. The decreased CL intensity was linear with isoniazid concentration in the range 0.001–1.0 μg·ml−1; and the detection limit was 0.35 ng·ml−1 (3s). The whole process, including sampling and washing, could be completed in 2 min with a relative standard deviation of less than 4.1%. The sensor could be reused more than 400 times and has been applied for the determination of isoniazid in pharmaceutical preparations. 相似文献
17.
A versatile method for the synthesis of carbamates from an ‘in-situ’ generated polymer-supported chloroformate resin is presented. BTC (bis-trichloromethyl carbonate) is used as phosgene equivalent to afford a supported chloroformate, which, by sequential ‘one-pot’ reaction with a variety of alcohols and amines, furnishes the corresponding carbamates in high yields and purities. 相似文献
18.
Reaction of 2,3,7,8,12,13,17,18-octaethylporphyrin with LiR reagents containing functional groups readily yields meso substituted derivatives suitable for further transformations with residues such as -p-C6H5Br, -p-C6H5-CCH, -p-C6H5-NH2 or -(CH2)3-CHCH2. Similar reactions of tetrabenzoporphyrin with alkyllithium reagents afforded the first entry into meso mono- and dialkylsubstituted tetrabenzoporphyrins while reaction of bicyclo[2.2.2]oct-type masked isoindole precursors with LiR followed by in situ retro-Diels-Alder reaction also afforded the 5-phenyl and 5,10-diphenyltetrabenzoporphyrins in high purity. 相似文献
19.
G. V. Kotelnikov Sophia P. Moiseyeva E. V. Mezhburd E. I. Maevsky Elena V. Grishina 《Journal of Thermal Analysis and Calorimetry》2005,81(2):255-259
Summary Measurements of energy transformation in mitochondria are done on a capillary differential titration calorimeter CTD2156. It is important to mention that a sediment is quickly formed by the mitochondria suspension without mixing by means of a vibrating needle. During the measurements, the vibrating needle is located inside the working volume of the chamber. The design of the calorimeter is substantiated theoretically. It provides a new mode of a reagent input in the measuring volume of the calorimetric chambers. It expands the spectrum of tasks that can be solved using this instrument. In the capillary calorimeter the calorimetric chambers unit is simple and small in size. These advantages of capillary chambers provide an opportunity to unite 20 capillary calorimetric chambers in one calorimetric block. It allows designing a multi-channel titration calorimeter. There are obvious advantages of such a calorimeter over other instruments in screening researches and in researches of objects maintaining stability only for a short time. 相似文献
20.
Ken-ichi Fujita Shigeru HashimotoAkihiro Oishi Yoichi Taguchi 《Tetrahedron letters》2003,44(19):3793-3795
After immobilizing arylselenenyl bromide on polymer resin, the oxyselenenylation reaction of olefin was carried out in water. An amphiphilic polymer-supported arylselenenyl bromide was employed, and various intramolecular oxyselenenylation and deselenenylation reactions proceeded smoothly in water in fair chemical yields (up to an 83% yield). 相似文献