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关于微量铅的测定,常见的有原子吸收法、分光光度法、阳极溶出伏安法等.关于络合物极话吸附法测定微量铅也有报道,但铅(Ⅱ)一向红菲步啉体系的极谱行为研究尚未见报道.该法灵敏度高,选择性较好,简单、快速.其线性范围为1.0×10~(-7)~4.0×10~(-6)mom/L,用于化妆品及牙膏中微量铅的测定,结果满意.2 实验部分2.1 试剂与仪器 1.00×10~(-2)mol/L 铅标准溶液:按常规方法配制(介质为0.2 mol/L HAc溶液);1.00×10~(-2)mol/L向红菲啰啉(BPT)溶液;l mol/LHAc溶液;l mol/L NaAc溶液.JP-3 型示波极谱仪,参比电极为饱和甘汞电极. 相似文献
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锡(Ⅳ)-3,4-二羟基苯甲酸-钒(Ⅳ) 体系极谱吸附催化波的研究 总被引:1,自引:0,他引:1
在含有 3.6×10-3mol/L 的 VOSO4、6.0×10-5mol/L 的 3,4-二羟基苯甲酸(DHBA)、 0.1mol/L 的甲酸盐缓冲溶液(pH3.3)体系中,Sn(Ⅳ)-DHBA 络合物产生一灵敏的吸附平行催化波,峰电位在 -0.52 V(vs.SCE).二次导数波高与锡浓度在 3.4×10-10~5.1×10-7mol/L 范围内呈良好线性关系.检出限达浓度 2×10-10mol/L .研究了催化波的性质和电极反应机理.方法已应用于罐头食品中微量锡的测定. 相似文献
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锡-芦丁极谱络合吸附波的研究 总被引:4,自引:0,他引:4
在pH3.9的HCOOH~HCOONa缓冲溶液中,用单扫示波极谱法可获得灵敏的Sn(Ⅳ)-芦丁(Rt)络合吸附波.在1.0×10~mol/L~6.0×10~mol/L范围内锡浓度与波高呈正比关系,检测下限可达6.0×10~(-9)mol/L.应用该法测定了罐头菠萝汁中的锡.测得电活性络合物的组成为Sn(Ⅳ):Rt=1∶1,条件稳定常数为2.7×10~4。对p_1波测得电极反应的表面电极反应速率常数(k_)_1=95s~(-1)。对P_2波测得电子转移系数α=0.60,表面电极反应速率常数(K_)_2=3.8s~(-1). 相似文献
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示波极地测定车间空气及其周围大气中的锡 总被引:1,自引:0,他引:1
用示波极谱法测定了焊锡车间空气及其周围大气中的锡。在 p H 2 .5的0 .1mol/ L 氯乙酸介质中 ,Sn( )与焦没食子酸形成的络合物在汞电极上还原可分别在 -0 .2 5 V和 -0 .45 V各产生一峰形良好的还原波。当有四价钒存在时 ,-0 .45 V处的波的峰电流大幅度增大 ,产生一灵敏的催化电流。该催化电流与锡浓度在 1× 10 -8~ 5× 10 -7mol/ L 范围内呈线性关系 ,检测限为 5× 10 -9mol/ L 相似文献
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邻苯三酚红修饰碳糊电级阳极溶出伏安法测定痕量锡的研究 总被引:6,自引:0,他引:6
研制了邻苯三酚红 ( PR)修饰碳糊电极 ,研究了采用该电极测定痕量锡的阳极溶出伏安法。在 0 .1 5 mol/L乙酸盐缓冲溶液 ( p H 4.5 )中 ,通过开路富集 ,Sn( )与修饰电极表面的邻苯三酚红生成络合物而富集于电极表面 ,然后介质交换至 4.0mol/L盐酸中 ,于 - 0 .80 V还原后再进行阳极化扫描 ,于 - 0 .69V左右获得一灵敏的 Sn的溶出峰 ,二次导数峰电流与 Sn( )浓度在 1 .68× 1 0 - 8~ 1 .68× 1 0 - 6mol/L范围内呈现良好的线性关系 ,检出限达 8× 1 0 - 9mol/L。对电极反应机理进行了讨论 ,方法已应用于罐头食品中锡的测定 相似文献
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用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%. 相似文献
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Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments. 相似文献
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The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula. 相似文献
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Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines. 相似文献
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KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields. 相似文献
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N. A. Nedolya 《Chemistry of Heterocyclic Compounds》2008,44(10):1165-1219
The review contains a concise historical account and information on the most significant researches undertaken by the staff
at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry
of Heterocyclic Compounds.
Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008. 相似文献
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Regiospecific and direct imidation of the methyl C(sp3)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products. 相似文献
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《Tetrahedron》2014,70(21):3377-3384
The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative. 相似文献
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Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields. 相似文献