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吐温20存在下铜(Ⅱ)-α,α′-联吡啶-2,2′-二氯-4,4′-二硝基重氮氨基苯分光光度研究及其分析应用 总被引:1,自引:0,他引:1
在吐温20存在的碱性溶液中,铜(Ⅱ)、α,α′-联吡啶与2,2′-二氯-4,4′-二硝基重氮氨基苯(2,2′-diCl-DNAAB)迅速形成1:1:2的三元络合物(在550nm处几乎无吸收),使试剂2,2′-diCl-DNAAB的最大吸收550nm处的吸光度迅速减小,借此测定痕量铜。适宜pH为10.8—11.7;在50毫升溶液中含有1.0—2.5毫升5%吐温20、1.0—320μmolα,α′-联吡啶、2.5—5.0毫升0.2mmol/L2,2′-diCl-DNAAB、4.0—12.0毫升乙醇对吸光度无影响。铜量在0—19微克/25毫升范围服从比尔定律;表观摩尔吸光系数为1.05×10~5。考查了60种离子或化合物对测定的影响。方法应用于工业废水和铁矿中微量铜的测定,结果令人满意。 相似文献
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Hyperbranched vinyl polymers were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization of a styrenic asymmetric divinyl monomer.This was achieved by using cumyl dithiobenzoate or S-dodecyl-S′- (α,α′-dimethyl-α″-acetic acid)trithiocarbonate as the chain transfer agent,1,1′-azobis(cyclohexanecarbonitrile) or thermal initiation as a source of radicals.Cross-linking was inhibited by a rapid RAFT-based equilibrium between active propagation chains and dormant species,and thus a h... 相似文献
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Propargylic carbonates reacted with dialkyl cycloalkanone-α,α′-dicarboxylates under thecatalysis of Pd(0)complex to give bicyclic compounds in high yields.The two electron-withdrawinggroups at α and α′positions of cycloalkanone rings are essential for the annulation reaction. 相似文献
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基于α,α′-联吡啶对H_2O_2氧化靛红的褪色反应的催化作用,本文建立了测定α,α′-联吡啶的新催化光度法,灵敏度为2.25×10 ̄(-9)mol·L ̄(-1),测定范围为0~4×10 ̄(-8)mol/25mL。 相似文献
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本文报导1,4-双(1′-苯基-3′-甲基-5′-氧代吡唑-4′-基)丁二酮(1,4)双缩邻氨基苯甲酸合双锌配合物的合成、表征、热分解反应动力学及电化学性质。运用Achar法与Coats-Redfern法对非等温动力学数据进行分析,推断第三步非等温热分解过程动力学方程为:dα/dt=3/2Ae-E/RT·(1-α)4/3[(1/(1-α)1/3-1]-1。第四步非等温热分解过程为一维扩散机理。其动力学方程为:dα/dt=Ae-E/RT·1/2α,运用粉末微电极技术测试了配合物的电化学性质,推断配合物为双电子一步的不可逆过程。 相似文献
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采用一种有效的方法合成了具有不同链长的二脂酰基α-D-半乳糖型甘油糖脂 。将半乳糖烯丙苷化,重结晶得到α-D-半乳糖烯丙苷。随后将糖环的羟基用苄 基保护,再利用OsO4/NMO(N-甲基-N-氧吗啉)的二羟基化条件将1-O烯丙基氧化 成为邻二羟基,得到3-O-(2′,3′,4′,6′-四-O-苄基-α-D-吡喃半 乳糖基)-sn-甘油。其与不同链长的脂酰氯进行脂酰化反应,然后氢解去掉苄基 得到五种二脂酰基α-D-半乳糖苷基甘油。利用^1H NMR,^13C NMR,2D NMR,IR和MS 对化合物的结构进行了确证。 相似文献
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A novel cross-linking process using two high molecular weight aromatic poly(thioether)s,which were synthesized by the reactions of 4,4′-thiobisbenzenethiol with 4,4′-difluorobenzophenone and 4,4′-difluorodiphenylsulfone,respectively, and commercially available lower molecular weight poly(p-phenylene sulfide)was investigated.These reactions were carried out in bulk by the addition of silver tetrafluroborate andα,α′-dibromo-p-xylene at 190℃over a period of 45 min. Furthermore,the same procedure could be modified to cross-link compression-molded films of these three polymers.The thermal and solubility behaviors of these polymers before and after cross-linking reactions,are presented. 相似文献
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Shu Yun Shi Qi Zhou Hua Peng Chang Xin Zhou Ming Hui Hu Qiao Feng Tao Xiao Jiang Hao Joachim Stoeckigt Yu Zhao 《中国化学快报》2007,18(11):1367-1370
Two new flavone glycosides,isoetin-7-O-β-D-glucopyranosyl-2′-O-α-L-arabinopyranoside (1) and isoetin-7-O-β-D-glucopyr- anosyl-2′-O-α-D-glucopyranoside (2),a new lignan,mongolicumin A (3),and a new guaianolide,mongolicumin B (4) were isolated from the aerial part of Taraxacum mongolicum.Their structures were elucidated mainly by spectral analyses. 相似文献
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XinHuaXU RuiLiangLU BingZHOU JianPingLI YinQuanDENG 《中国化学快报》2004,15(2):145-147
The title compound 5 was synthesized in 45% yield by the reaction of compound 3 with α,α′-bis (bromomethyl)-2, 2′-bipyridine in CH3CN at 70℃ for 24 h. 相似文献
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利用红外线气体分析仪测定了冬小麦燕大1817和东方红3号在受到条锈菌(Puccinia striiformis West)侵染后叶片光合作用的变化。证明严重度S越高,残余健部光合作用极大值P′_(max)越低,其关系为P′_(max)=P′_(max)(1-0.826*S)。根据试验数据推导建立了条锈病导致的光合产物降低率预测模型:L_(光合)=1-(P_(max)+I_(1α))/(P′_(max)+I_(1α))(1-bS)(1-S),和理论模型L_(光合)=aS~n,n=f(P′_(max)/P_(max))。最后讨论了L_(光合)与验经产量损失模型的关系。 相似文献