抗坏血酸-偶氮胭脂红B体系催化光度法测定痕量铜

１引言催化光度法测定铜已有很多篇报道．本文基于ＨＡｃ－ＮａＡｃ介质中，痕量Ｃｕ（Ⅱ）对抗坏血酸还原偶氮胭脂红Ｂ的褪色反应的催化作用，建立了催化光度法测定痕量铜的新方法。方法灵敏度为３．２６×１０－９ｇ／Ｌ；测定范围为０～２μｇ／ＬＣｕ２＋；对１０ｍＬ体积中１５ｎｇＣＵ２＋重复测定１１次的相对标准偏差为１．２８％。本法是目前同类方法中灵敏度最高，选择性和重现性最好的体系之一。应用于血清、面粉和白酒中痕量铜的测定，结果令人满意。２实验部分２．１主要仪器和试剂７２２型分光光度计。铜标准溶液用ＣＵＳＯ４…     

极谱催化波法测定黄连素

基于黄连素在过氧化氢存在下产生的极谱催化波,拟定了测定黄连素的新方法。在８．０×１０－２ｍｏｌ／ＬＮａ２Ｂ４Ｏ７－Ｎａ２ＣＯ３（ｐＨ９．４±０．４）－４．０×１０－３ｍｏｌ／ＬＨ２Ｏ２底液中,催化波峰电流与黄连素浓度在 １．０ × １０－８～ ３．０ × １０－７ｍｏｌ／Ｌ范围内呈线性关系。催化波的灵敏度比相应黄连素还原波高２５倍。     

催化动力学光度法测定痕量锰（Ⅱ）

研究了在Ｎａ２ＨＰＯ４－ＮａＯＨ介质中，Ｍｎ（Ⅱ）催化高碘酸钾氧化镁试剂１［４－（对硝基苯偶氮）间苯二酚］的反应及其动力学条件，建立了一种高灵敏、高选择性测定痕量Ｍｎ（Ⅱ）的新方法。可测０．０１－２．５μｇ／２５ｍＬ范围的锰（Ⅱ），方法的检测限为６．４３×１０＾－１１ｇｍ／ｍＬ。     

高灵敏催化光度法测定痕量钴

基于在氢氧化钠介质中，钴（Ⅱ）催化过氧化氢氧化５－溴水杨基荧光酮褪色的反应，建立了催化动力学光度法测定痕量钴的新方法，方法检出限为１．１×１０＾－１０ｇ／Ｌ，线性范围为２．５－８０ｎｇ，已成功地用于维生素Ｂ１２、人发及茶叶中痕量钴的测定。     

砷的氢催化波研究及硫中微量砷的测定

砷在１．５×１０＾－４ｍｏｌ／Ｌ Ｃｏ－０．１ｍｏｌ／Ｌ ＫＣＮＳ－１％抗坏血酸－０．７ｍｏｌ／Ｌ Ｎａ２ＳＯ４－４×１０＾－３ｍｏｌ／Ｌ ＮａＢｒ介质中产生一灵敏催化波，峰电位为－１．１Ｖ。采用微分脉冲极谱法研究了各项实验条件，建立了直接测定硫中微量砷的方法。该法简便快速，结果满意。     

催化动力学光度法测定痕量苯酚

研究了在硫酸介质中苯酚对Ｉ＾－１催化Ｃｅ＾４＋－Ａｓ（Ⅲ）反应的抑制作用及其动力学条件。建立了用催化动力这光度法测定痕量苯酚的新方法，结果表明，在０．００１ｍｏｌ／ＬＣｅ（ＳＯ４）２，０．００１２５ｍｏｌ／Ｌ，Ａｓ２Ｏ３，０．０１ｍｇ／Ｌ，ＫＩ，０．０１２５ｍｏｌ／Ｌ，Ｈ２ＳＯ４和０．１３％（ｗ／ｖ）ＮａＣｌ溶液中测定苯酚，其表面摩尔吸光系数为２．１×１０＾５Ｌ．ｍｏｌ＾－１．ｃｍ＾－１，线性范围     

二溴硝基偶氮氯膦催化动力学光度法测定痕量钴的研究

研究了在ｐＨ７．０磷酸盐介质中，钴催化Ｈ２Ｏ２氧化二溴硝基偶氮氯膦色反应，建立了催化光度法测定痕量钴的新方法，其检出限为５×１０＾－７ｇ／Ｌ，在０．５－３２μｇ／Ｌ范围内，钴与ｌｇ呈良好的关系。     

镍—甘氨酸化合物氢催化波研究

本研究了在ｐＨ＝１０的Ｎａ２Ｂ４Ｏ７·１０Ｈ２Ｏ－ＮａＯＨ缓冲液中，在乙醛共存下，镍－甘氨酸形成化合物的氢催化波以及电极过程的反应机理。对镍和甘氨酸的极谱图进行了测定，并且研究了Ｎｉ＾２＋和甘氨酸的量对峰形和峰电流的影响，以及最佳测定的ｐＨ条件，指出了在２×１０＾－４￣１．２·１０＾－３ｍｏｌ／Ｌ间峰电流与甘氨酸浓度呈线性关系。本还对该氢催化波的产生机理进行了理论和实验探讨。循环伏安法表示了电     

过氧化氢氧化二甲苯蓝AS催化光度法测定痕量钴的研究

研究了在碱性条件下,痕量钴（Ⅱ） 与三乙醇胺协同催化Ｈ２Ｏ２氧化二甲苯蓝ＡＳ指示反应的动力学行为,建立了测定痕量钴的新催化动力学分析法。质量浓度的线性范围为０～２．９ μｇ／２５ ｍ Ｌ,检出限为１．３×１０－ ７ ｇ／Ｌ。讨论了催化反应机理,测定了茶叶、人发等样品中钴的含量。     

钴(Ⅱ)催化偶氮胭脂红B的褪色反应特性及应用

基于氢氧内介质中痕量钴对过氧化氢氧化偶氮胭脂红Ｂ的褪色反应的强烈催化作用,建立了催化光度法测定痕量钴的新方法。方法灵敏度为５．２４×１０＾－１２ｇ／ｍＬ,测定范围为０￣３５ｎｇ／１０ｍＬ,对质量浓度为３μｇ／Ｌ的Ｃｏ（Ⅱ）重复测定１１次的相对标准偏差为２．１６％。方法应用于维生素Ｂ１２和矿泉水中痕量钴的测定,结果满意。     

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.     

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.     

Copper-catalyzed multicomponent reactions of 2-iodoanilines,benzylamines, and elemental sulfur toward 2-arylbenzothiazoles

A relatively cheap copper salt-catalyzed, three-component approach providing 2-arylbenzothiazoles in good to excellent yields from readily available 2-iodoanilines, benzylamines, and sulfur powder is reported. This methodology allows preparation of various classes of 2-arylbenzothiazoles and provides a general, reliable approach.