催化褪色光度法测定痕量铜的新体系

研究了硫酸介质中铜 ( )催化高碘酸钾氧化中性红褪色反应的适宜条件 ,建立了动力学光度法测定痕量 Cu( )的新方法。Cu( )的质量浓度在 0～0 .5μg/2 5 m L范围内与ΔA值呈良好的线性关系 ,检出限为 3.5× 10 -8g/L。已用于饮用水和海产品中铜的测定     

吖啶黄催化荧光法测定痕量铜的研究

研究了在氨-氯化铵缓冲介质中,Cu(Ⅱ)催化过氧化氢氧化吖啶黄退色,利用使其荧光减弱的指示反应,建立了催化荧光法测定痕量铜的新方法.铜的线性范围为8.0×10~4～8.O×10~(-3)μg·ml~(-1),检出限为5.0×10~(-4)μg·ml~(-1).方法应用于水、人发和纯铝中痕量铜的测定,结果满意.     

Cu(Ⅱ)催化抗坏血酸还原偶氮肿Ⅲ褪色反应的研究和应用

研究了在HOAc-NaOAc介质中,用2,2′-联吡啶作活化剂,Cu(Ⅱ)催化抗坏血酸还原偶氨肿Ⅲ褪色反应的适宜条件和影响因素,建立了测定痕量铜的新方法.测定范围为0～0.22μg/25ml,方法灵敏度为2.04×10~(-11)g·ml~(-1).直接用于童发和食品中铜的测定,结果满意.     

催化光度法测定痕量铜

痕量铜对生命活动很重要。人体中铜的代谢与铁的代谢有相关性,铜参于造血过程,缺铜会引起贫血病。因此鉴于铜的重要生理作用,各生物样品中痕量铜的测定日益受到重视。已有文献[2,3]报道利用催化光度法测定铜。但高碘酸钾-溴邻苯三酚红体系尚未见报道,铜在乙酸-乙酸钠介质中对上述体系有催化褪色作用。据此建立了测定痕量铜的新方法。本法测定范围为0～5μg/10ml,表观摩尔吸光系数ε=1.26×10~5,用于茶叶中铜的测定得到较好结果。1 试验部分1.1 主要试剂与仪器 Cu（Ⅱ）标液:0.1mg·ml~(-1),准确称取CuSO_4·5H_2O 0.0982g,用去离子水溶解。稀释于50ml量瓶中。工作液稀释为0.1μg·ml~(-1) 溴邻苯三酚红溶液:1.0×10~(-3)mol·L~(-1) 高碘酸钾溶液:5.0×10~(-4)mol·L~(-1) 乙酸-乙酸钠缓冲液:pH=6.0 1,10-菲罗啉溶液:2g·L~(-1) 试剂均为分析纯,水为去离子水     

Cu(Ⅱ)-KIO4-胭脂红-1,10-菲罗啉体系催化动力学光度法测定人发中痕量铜

基于pH6.5的Na2HPO4-NaH2PO4缓冲介质中铜离子对高碘酸钾氧化胭脂红褪色反应的催化作用,提出了催化动力学光度法测定痕量铜的新方法.研究了该方法的适宜反应条件,方法的检出限为1.1×10-7g/L Cu(Ⅱ),表观摩尔系数ε=7.8×105L·mol-1·cm-1,线性范围为0～0.5μg/10mLCu(Ⅱ),方法已用于人发中痕量铜的测定.     

催化动力学光度法测定人发中的痕量铜

在NH3.H2O介质中,微量Cu(Ⅱ)能显著催化过硫酸铵氧化溴百里酚蓝的褪色反应。研究了该褪色反应的最佳反应条件,建立了催化动力学测定铜的新分析方法。本法测定铜的线性范围在0.00~0.08μg.mL-1。回收率在97.5%~99.0%之间,RSD为0.6%~1.6%,检出限为4.8×10-8g.L-1。用于人发中痕量Cu(Ⅱ)的测定,结果满意。     

茜素红S催化动力学光度法测定痕量铜(Ⅱ)及机理探究

研究了在pH 5.0的柠檬酸-NaOH缓冲介质中,以邻菲口罗啉(phen)作活化剂,痕量Cu(Ⅱ)对H2O2氧化茜素红S(ARS)的褪色反应存在明显的催化作用,由此建立了测定痕量Cu(Ⅱ)的催化动力学光度法。应用了正交试验法确定最佳条件,测定了有关动力学参数。该方法的检出限为6.3×10-9g/mL,线性范围为0~0.8μg/mL,应用于茶叶、自来水等水样中痕量铜的测定。同时,对反应机理进行了探究。     

Cu（Ⅱ）-H2O2-考马斯亮蓝G250体系催化光度法测定痕量铜

在NH3-NH4Cl缓冲溶液介质中,痕量Cu2+对H2O2氧化考马斯亮蓝G250(CBBG)褪色反应的显著催化作用,建立了催化动力学光度法测定痕量铜的新方法。线性范围为0.02～0.20μg/mL,检出限为1.34×10-9g/mL。考察了20多种共存离子的影响。方法用于发样中痕量铜离子的测定,相对标准偏差小于3.4%,加标回收率为97%～105%。     

催化褪色光度法测定痕量铜——胭脂红—铜—过氧化氢体系

研究了在磷酸二氢钾-四硼酸钠介质中,用邻菲罗啉作活化剂,CU(Ⅱ)催化过氧化氢氧化胭脂红的褪色反应及反应活化能的测定,建立了测定痕量铜的新方法.铜的测定范围为0～0.4μg/25ml,方法灵敏度为2.35×10~(-11)g·ml~(-1),用于合成水样及人发样中的痕量铜测定,结果满意.     

铜(Ⅱ)催化邻甲氧基酚的氧化自聚反应研究与应用

研究了在硼酸 -氢氧化钠缓冲介质中 ,痕量 Cu( )催化邻甲氧基酚的氧化自聚反应的最佳条件、动力学参数及反应机理 ,建立了催化动力学光度法测定痕量铜的新方法。方法的线性范围为 0～ 1 80 ng/2 5m L,检出限为 4.9× 1 0 -11g/m L。已应用于铅锌矿废渣中铜的测定     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

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%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

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.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

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.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

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.