催化褪色反应动力学法测定痕量铜

作者发现铜(Ⅱ)对过氧化氢在硫酸介质中氧化甲基橙的褪色反应有催化作用,找到了影响催化褪色反应的最佳条件,建立了测定痕量铜(Ⅱ)的新方法。灵敏度为9.22×10~(-11)g/ml,测定范围0～2.0μgCu~(2+)/50ml。用于测定几种实物样品中的痕量铜,得到满意的结果。相对标准偏差0.2％～2.3％。     

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.     

催化还原褪色光度法测定蒙药中痕量铜(Ⅱ)

在增敏剂溴化十六烷基三甲胺和活化剂α、α-联吡啶存在的条件下,以铜(Ⅱ)催化抗坏血酸还原偶氮氯膦mA褪色为指示反应建立了动力学光度法测定痕量铜的新方法。用固定时间法在554 nm处检测催化反应,方法的线性范围为0~0.11μg/mL,检出限6.3×10-11g/mL,相对标准偏差为3.6%。用于多种蒙药样品中痕量铜的测定。     

水及血液中痕量铜的化学发光分析

本文采用自制仪器对鲁米诺-氰化钾-铜(Ⅱ)化学发光体系进行了系统研究,选定了测铜的最佳条件。该体系以铜(Ⅱ)作为氧化剂直接氧化鲁米诺产生λ_(max)为425nm的闪烁化学发光。测铜的线性范围为2×10~(-10)—6×10~(-7)/ml,检测下限为9×10~(-l2)g/ml,对10~(-10)g/ml铜(Ⅱ)测定的变异系数为4.6％。采用焦磷酸钠作为掩蔽剂可消除常见共存离子的干扰。此法用于水及人体全血中痕量铜的测定,结果均比较满意。     

新指示反应催化光度法测定痕量铜的研究

研究了在盐酸介质中,铜催化抗坏血酸还原甲基橙的新指示反应,测定了反应表观活化能,探讨了反应机理,建立了测定痕量铜的催化光度新方法,线性范围为0～0.10μg/25ml,检出限为1.32×10~(-11)g·ml~(-1)。     

催化光度法测定痕量铜——Cu(Ⅱ)-KIO_4-酸性品红-α,α′,-联吡啶体系

本文研究了在α,α′-联吡啶存在下,铜(Ⅱ)离子催化高碘酸钾氧化酸性品红褪色的新指示反应及动力学条件,建立了催化光度法测定痕量铜的方法。检出限为5.3×10~(-10)g/mL,线性范围为0～0.5μg/10mL。操作简单、快速,用于测定饮用水和人发中的铜含量获得满意的结果。     

铜(Ⅰ)-4,4''''-四乙基二胺二苯甲硫酮-表面活性剂体系的分光光度研究

在PH3.4—7.2的磷酸盐缓冲溶液中,铜(Ⅰ)与4,4＇-四乙基二胺二苯甲硫酮(TEDAT)在乳化剂OP存在下生成橙红色的络合物。该络合物摩尔吸光系数为1.33×10~5l·mol~(-1)·cm~(-1)·其组成比为Cu:TEDAT=1:4,在0—10μgCu/25ml范围内符合比尔定律。本法具有良好的选择性,曾用于水、纯铝及铝合金中微量铜的测定,结果满意。     

铜(Ⅱ)-铬天青S-过氧化氢体系催化光度法测定痕量铜

本文研究了在氨水介质中,痕量铜对过氧化氢氧化铬天青S褪色反应的催化作用,建立了一个催化光度法测定痕量铜的新方法。线性范围为0～20ng/mL,检出限为5.59×10~(-11)g/mL,并用于铝合金标准样品,环境标准样品和自来水中痕量铜的测定。     

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.     

过氧化氢氧化二氯荧光素动力学荧光法测定痕量铜

研究了在氨性介质中，铜(Ⅱ)催化过氧化氢氧化二氯荧光素的褪色反应，建立了动力学荧光法测定痕量铜的新方法。方法的检出限为0．06μg/L，测定铜的线性范围为0．2～4．0μg/L。已用于人发、茶叶和自来水中痕量铜的测定。     

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.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

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.     

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.     

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.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.