共查询到20条相似文献,搜索用时 15 毫秒
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电化学方法简便测定芬顿反应产生的羟基自由基 总被引:5,自引:0,他引:5
1 引 言由于羟基自由基的反应活性大、寿命短、存在浓度低 ,直接测定存在一定的难度。因此 ,建立快速、简便的测定方法 ,对自由基理论研究和抗氧化药物筛选有重要意义。水杨酸、2 脱氧 D 核糖和DMSO是测定羟基自由基常用的分子探针。其中 ,DMSO与羟基自由基反应 ,主要的生成物有甲基亚磺酸 (I)及甲醛 (II)等。·OH +(CH3) 2 SOCH3SO2 H +·CH3(1)·CH3+O2 CH3OO· (2 )2CH3OO·HCHO(II) +CH3OH +O2 (3) 有报道通过测定上述反应生成的甲基亚磺酸或来间接定量测定羟基自由基 ,也有… 相似文献
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Abstract In precediig papers the authors have reported on the syntheses of polvrners containing a neYi type of free rarlical verdazyl [1, 2] through the anionic polymerizatim cf vinyl verdazyl monomers [3, 4]. In tNs paper we wish to report on the synthesis of polymer verdazyl by the reaction of verdazyl having amino group I with copolymers of maieic annvdride. 相似文献
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Vijay Kumar Thakur Manju Kumari Thakur Raju Kumar Gupta 《International Journal of Polymer Analysis and Characterization》2013,18(7):495-503
The present research work deals with the surface modification of natural cellulosic polymers to develop novel materials for different applications. Natural cellulose-graft-poly (methyl acrylate) copolymers were prepared using the free radical induced graft copolymerization technique. Different reaction parameters were optimized to achieve the highest percentage of grafting of natural cellulose-graft-poly (methyl acrylate) copolymers. The natural cellulose graft copolymers were characterized by FT-IR, SEM, TGA, and physicochemical studies. For the evaluation of swelling and the physicochemical mechanism, swelling and chemical resistance studies were carried out in different solvents as well as chemicals. 相似文献
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Dragos Popescu Richard Hoogenboom Helmut Keul Martin Möller 《Macromolecular Symposia》2010,296(1):49-52
Hydroxy functional acrylates were prepared via transacylation of methyl acrylate with 1,2,6-hexanetriol catalyzed by Candida antarctica lipase B. Under the applied reaction conditions, 70% of the substrate was converted into hydroxy functional acrylates. In a subsequent step, after filtration of the enzyme, the monomer mixture containing methyl acrylate and the new monomers was polymerized via free radical polymerization resulting in a functional copolymer with Mn = 14500 g/mol. 相似文献
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Summary. The addition of triphenylphosphine to dimethyl acetylenedicarboxylate in the presence of arylsulfonylglycyl chlorides leads
to 1,4-bis-arylsulfonyl-tetrahydropyrazine-2,5-diones and dimethyl (E)-2-chloro-2-butenedioate.
Corresponding author. E-mail: isayavar@yahoo.com
Received June 3, 2002; accepted June 10, 2002 相似文献
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William J. Bailey Takashi Endo Benjamin Gapud Yin-Nian Lin Zhende Ni Cai-Yuan Pan 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(8-9):979-995
Since free radical ring-opening polymerization made it possible to introduce functional groups, such as esters, carbonates, thioesters, and amides, into the backbone of an addition polymer, it was reasoned that simple hydrolysis of these copolymers would produce the desired oligomers that could be terminated with various combinations of hydroxyl, amino, thiol, and carboxy1 groups. Thus the copolymerization of 2-methylene-1,3-dioxepane and styrene (r1=0.021 and r2=22.6) gave a copolymer containing 10 mole-percent of an ester-containing unit with 100% ring opening at 120°C. Hydrolysis of this copolymer gave an oligomer terminated with a hydroxyl group and a carboxylie acid group. Similarly the copolymerization of 2-methylene-1,3-dioxepane and ethylene gave a series of biodegradable polyethylene copolymers containing 2.1 to 10.4% ester-containing units. Hydrolysis of these copolymers gave a series of ethylene oligomers with nine to forty-seven ethylene units and terminated with a hydroxyl group and a carboxylic acid group. By the same general method oligomers of various monomers that are terminated with a methylandno group and a carboxylic acid group from N-methyl-Z-methylene-1,3-oxazolidine and with a thiol group and a carboxyl group from Z-methylene-1,3-oxathiolane. 相似文献
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Free Radical Hydrophosphorylation of Fluoroalkyl Vinyl Ethers: Synthesis of Fluoroalkyl Phosphonates
L. A. Oparina M. Ya. Khilko N. A. Kolyvanov N. K. Gusarova N. A. Nedolya V. N. Saprygina K. A. Apartsyn V. V. Kireeva B. A. Trofimov 《Russian Journal of General Chemistry》2020,90(4):614-618
An effective method for the synthesis of dialkyl [2-(polyfluoroalkoxy)ethyl]phosphonates by free radical hydrophosphorylation of fluoroalkyl vinyl ethers with dialkyl (H)-phosphonates was developed. The reaction proceeds in the presence of catalytic amounts of azabisisobutyric acid dinitrile (AIBN) (150°C, 2 h, portionwise addition of AIBN) to afford the target fluoroalkyl phosphonates in up to 85% isolated yield. 相似文献
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Christian Gardrat 《合成通讯》2013,43(13):1191-1192
An improved synthesis of norbisabolide (1) is described starting from limonene. Free radical addition of acetic acid in the presence of manganese (III) acetate led to an ethylenic acid which is converted to (1) in acidic medium. 相似文献
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Unique chemical structures that are often characteristic of biologically active natural products are often created by oxidative cyclizations. Many of these reactions are catalysed by ‘non-canonical’ or ‘thwarted’ iron oxygenases that appear to involve long-lived radicals. This perspective summarizes our group‘s efforts to mimic these biosynthetic transformations for the synthesis of highly oxidized dibenzocyclooctadiene lignan natural products using redox neutral photocatalysis. We describe the evolution of this research program, which hinges on the use of Okada's redox active ester, and show how multiple factors control the fate of the resulting radicals. 相似文献
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SHA Chin-Kang CHIU Rei-Torng LIH Shinn-Horng SANTHOSH K. C. CHANG Ching-Jung TSENG Wei-Hong HO Wen-Yueh 《有机化学》2003,23(Z1):67-67
Intramolecular radical cyclization reactions are now used routinely to synthesize carbocyclic and heterocyclicstructures. We have reported that α-carbonyl radicals 1, generated from the corresponding iodo ketones or enones,underwent intramolecular radical cyclization smoothly to afford products 2. [1,2] 相似文献
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水杨酸甲酯清除羟基自由基活性的研究 总被引:1,自引:0,他引:1
利用脉冲辐解技术研究了水杨酸甲酯清除羟基自由基反应的瞬态吸收谱,测定了水杨酸甲酯与羟基自由基反应的表观速率常数。辅以常规检测方法,测定了水杨酸甲酯对羟基自由基的清除率。结果表明,水杨酸甲酯能快速有效清除羟基自由基。探讨了水杨酸甲酯清除羟基自由基的反应机制。 相似文献
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N-乙烯基咔唑三羰基铬的合成和自由基聚合反应 总被引:2,自引:0,他引:2
合成一种新的金属铬有机单体N-乙烯基咔唑三羰基铬,经元素分析、IR和1HNMR确证和表征.研究结果表明,N-乙烯基咔唑三羰基铬能发生自由基聚合反应,得到结构单元含等物质的量铬的金属有机高分子,苯环及含氮给电子中心的共轭效应能在一定程度上弥补由Cr(CO)3基团吸电子诱导效应引起的单体聚合活性的下降 相似文献