聚乙二醇-硫酸铵-亚硝基R盐体系中钴(Ⅱ)的分离及其存在形态

在 ｐＨ ４．０～６．０的 ＨＡｃ－ＮａＡｃ缓冲溶液中，Ｃｏ（Ⅱ）、Ｆｅ（Ⅲ）、Ｎｉ（Ⅱ）、Ｃｕ（Ⅱ）等金属离子与亚硝基Ｒ盐可形成稳定络合物。加入ＨＣＩ适当提高溶液酸度（ＨＣＩ浓度在０．３～０．６ｍｏｌ／Ｌ），用聚乙二醇２０００（ＰＥＧ）－硫酸铵－亚硝基Ｒ盐体系萃取，Ｃｏ（Ⅱ）可被ＰＥＧ相几乎完全萃取，而Ｆｅ（Ⅲ）、Ｎｉ（Ⅱ）、Ｃｕ（Ⅱ）基本上不被萃取。实现了Ｃｏ（Ⅱ）、Ｆｅ（Ⅲ）、Ｎｉ（Ⅱ）、Ｃｕ（Ⅱ）混合离子合成样品和硅酸盐岩矿实际样品中Ｃｏ（Ⅱ）的分离与测定。同时吸收光谱、摩尔比、连续浓度变换、加入表面活性剂等实验表明，在萃取相Ｃｏ（Ⅱ）与亚硝基Ｒ盐是１：３络阴离子形式存在的。     

聚乙二醇—硫酸铵—亚硝基R盐体系中钴（Ⅱ）的分离及其存在形态

在ｐＨ４．０～６．０的ＨＡｃ－ＮａＡｃ缓冲溶液中，Ｃｏ（Ⅱ），Ｆｅ（Ⅲ），Ｎｉ（Ⅱ），Ｃｕ（Ⅱ）等金属离子与亚硝基Ｒ盐可形成稳定络合物，加入ＨＣｌ适当提高溶液酸度（ＨＣｌ浓度在０．３～０．６ｍｏｌ／Ｌ）用聚乙二醇２０００（ＰＥＧ）－硫酸铵－亚硝基Ｒ盐体系萃取，Ｃｏ（Ⅱ）可被ＰＥＧ相几乎完全萃取，而Ｆｅ（Ⅲ），Ｎｉ（Ⅱ），Ｃｕ（Ⅱ）基本上不被萃取，实现了Ｃｏ（Ⅱ），Ｆｅ（Ⅲ），Ｎｉ（Ⅱ），Ｃｕ（Ⅱ）     

邻联甲苯胺-过氧化氢催化光度法测定钴

１引言 在碱性介质中,痕量Ｃｏ（Ⅱ）见对Ｈ２Ｑ２氧化邻联甲苯胺（ｏ－Ｔｏｌｉｄｉｎｅ）的显色反应具有强烈的催化作用,探讨了利用该反应进行痕量Ｃｏ（Ⅱ）测定的影响因素,建立了测定痕量Ｃｏ（Ⅱ）的催化动力学光度法,该方法的灵敏度为１．７８ × １０－６ｇ／Ｌ,测定的线性范围为０．８～３．６ μｇ／Ｌ Ｃｏ２＋,应用于维生素Ｂ１２中痕量Ｃｏ（Ⅱ）的测定,结果满意。２实验部分２．１仪器与试剂 ７２１－１００型分光光度计;电热恒温水浴槽;Ｎｉｃｏｌｅｔ ＦＴ－ＩＲ ５ＤＸ红外光谱仪。钴（Ⅱ）标准溶液：１ｍｇ／Ｌ;…     

钴(Ⅱ)-β-巯基丙酸-NaNO_2体系的极谱催化波研究

在ｐＨ３．８的Ｈ２ＳＯ４－ＮＨ４Ａｃ介质中，Ｃｏ（Ⅱ）－β－巯基丙酸（ＭＰＡ）－ＮａＮＯ２体系产生－灵敏的极谱催化波，峰电位在－０．８４Ｖ（ｖｓ．ＳＣＥ），钴浓度在０．０２～１００ｎｇ／ｍＬ范围内与峰电流呈线性关系。检出限为０．０１ｎｇ／ｍＬ。本文对极谱波的性质和机理进行了初步探讨。本法用于土壤中总钴和有效钴的测定，结果满意。     

用Tween80—硫酸铵—1—（2—吡啶偶氮）—2—萘酚—磺酸体系萃取马（Ⅱ）,钴 …

研究了Ｔｗｅｅｎ８０水溶液在（ＮＨ４）２ＳＯ４存在下,水溶性螯合剂１－（２－吡啶偶氮）－２－萘酚－磺酸与金属离子螯合物在该体系中两相间的分配行为。结果表明,Ｐｄ（Ⅱ）,Ｃｏ（Ⅱ）,在ｐＨ２．０－３．５缓冲溶液中可被Ｔｗｅｅｎ相完全萃取,而Ｚｎ（Ⅱ）,Ｃｄ（Ⅱ）,Ｍｎ（Ⅱ）,Ａｌ（Ⅲ）基本上不被萃取。     

新体系Co—H2O2—OCPF催化褪色光度法测定痕量钴的研究

本文研究了在碱性介质中，钴（Ⅱ）对过氧化氢氧化邻氯苯基荧光酮（ＯＣＰＦ）褪色反应，建立了催化光度法测定痕量钴的新方法。其检出限为８．２ｐｇ／ｍＬ，在０－３．５ｎｇ／ｍＬ范围内，钴（Ⅱ）与ｌｏｇ（Ａｏ／Ａ）有良好好线性关系。该指示反应灵敏度选择性好，应用于维生素Ｂ１２和污水中钴的测定获得满意结果。     

非有机溶剂萃取分离贵金属的研究——聚乙烯基吡咯烷酮-盐-水固-液萃取分离金、铂、钯溴络阴离子

道了聚乙烯基吡咯烷酮（ＰＶＰ）－（ＮＨ４）２ＳＯ４－水的固－液萃取体系中Ａｕ（Ⅲ）、Ｐｔ（Ⅳ）、Ｐｄ（Ⅱ）溴络阴离子的萃取行为，在ＨＢｒ介质中，可萃取贵金属Ａｕ（Ⅲ）、Ｐｔ（Ⅳ）、Ｐｄ（Ⅱ）而与贱金属Ｆｅ（Ⅲ）、Ｃｏ（Ⅱ）、Ｎｉ（Ⅱ）、Ａｌ（Ⅲ）、Ｃａ（Ⅱ）、Ｍｇ（Ⅱ）、Ｃｕ（Ⅱ）等分离，对合成样及实际样品进行了定量萃取分离测定，结果与其它方法相符，并对机理进行了初步探讨。     

钴（Ⅱ）—β—巯基丙酸—NaNO2体系的极谱化波研究

在ｐＨ３．８的Ｈ２ＳＯ４－ＮＨ４Ａｃ介质中，Ｃｏ（Ⅱ）－β－巯基丙酸（ＭＰＡ）－ＮａＮＯ２体系产生－灵敏的极谱催化波，峰电位在－０．８４Ｖ（ｖｓ．ＳＣＥ）钴浓度在０．０２～１００ｎｇ／ｍＬ范围内与峰电流呈线性关系，检出限为０．０１ｎｇ／ｍＬ。本文对极谱波的性质和机理进行了初步探讨，本法用于土壤中总钴和有效钴的测定，结果满意。     

用聚乙二醇—硫酸铵—铝试剂体系萃取分离铁（Ⅲ）铝（Ⅲ）,铜（Ⅱ）钴（Ⅱ）…

研究了在聚乙二醇－硫酸铵－铝试剂体系中Ｆｅ（Ⅲ），Ａｌ（Ⅲ）、Ｃｕ（Ⅱ）、ＣｏⅡ）Ｃｄ（Ⅱ）Ｍｎ（Ⅱ）、Ｎｉ（Ⅱ）的萃取分离行为。结果表明，在ＰＨ５．０－６．５ＨＡｃ－ＮａＡｃ缓冲溶液中，Ｆｅ（Ⅲ）、Ａｌ（Ⅲ）可被ＰＥＧ相几乎完全萃取，而Ｃｕ（Ⅱ）、Ｃｏ（Ⅱ）Ｃｄ（Ⅱ）Ｍｎ（Ⅱ）基本上不被萃取，从而实现了Ｆｅ（Ⅱ）与Ｃｕ（Ⅱ）Ｃｏ（Ⅱ）Ｃｄ（Ⅱ）Ｍｎ（Ⅱ)及Ａｌ（Ⅲ）与Ｆｅ（Ⅲ）Ｃｏ（Ⅱ）、Ｃｕ（     

5—（4—甲氧基苯偶氮）—8—（苯磺酰氨基）喹啉的合成及其与钴荧光反应的研究

本文报告了５－（４－甲氧基苯偶氮）－８－（苯磺酰氨基）喹啉（ＭＯＰＢＳＱ）的合成及结构鉴定，建立了ＭＯＰＢＳＱ－吐温８０测钴的新荧光分析方法。方法的检测限为０．５ｎｇ／ｍＬ，线性范围为０～４０μｇ／Ｌ螯合物在λｅｘ／λｅｍ＝３４１ｎｍ／４０５ｎｍ和产生经烈荧光。不经分离可直接用于维生素Ｂ１２及蔬菜中痕量钴的测定。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

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%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

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 substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.