KBrO3—KBr紫外分光光度法测定痕量水杨酸

研究了ＨＣｌ溶液中ＫＢｒＯ３－ＫＢｒ紫外分光光度法测定水杨酸的条件,建立了测定痕量水杨酸的新方法。结果表明,在０．６ｍｏｌ／ＬＨＣｌ,３＊１０＾－５ｍｏｌ／ＬＫＢｒＯ３,５＊１０＾－４ｍｏｌ／ＬＫＢｒ,６＊１０＾－４ｍｏｌ／ｌＫＩ溶中测定水杨酸,其线性范围为０．２－４．０ｍｇ／Ｌ,表观摩尔吸光系数为１．９＊１０＾－４Ｌ．ｍｏｌ＾－１．ｃｍ＾－１,Ｓａｎｄｅｌｌ为７．３μｇ／ｃｍ＾２。ｓｇ ｉｆ ｅ     

铜钨杂多酸—耐尔蓝离子缔合显色反应及其应用

在阿拉伯胶存在下铜钨多酸与耐尔蓝形成离子缔子缔合物，其最大吸收位于５８０ｎｍ；表观摩尔吸光度ε值为２．２２＊１０＾６Ｌ．ｃｍ ＾－１；铜量在０－２４μｇ／Ｌ范围内服从比耳定律；检测限（３σ）１．０μｇ／Ｌ（ｎ＝１０）；分析１６μｇ／Ｌ铜的ＲＳＤ＝１．５％（ｎ＝１１）；离子缔合物的摩尔比为Ｃｕ：Ｗ：ＮＢ＝１：１２：４。     

流动注射化学发光抑制法测定抗坏血酸

基于抗坏血酸对Ｌｕｍｉｎｏｌ－ＫＩＯ４－Ｈ２Ｏ２体系化学发光反应的抑制作用,建立了化学发光抑制快速测定抗坏血酸的新方法。该方法线性范围为１．０＊１０＾－７－１．０＊１０＾－５ｍｏｌ／Ｌ,检出限为６．０＊１０＾－８ｍｏｌ／Ｌ,对８．０＊１０＾－７ｍｏｌ／Ｌ抗坏血酸１１次平行测定的相对标准偏差为１．０％。用于维生素Ｃ片剂及注射液中抗坏血酸含量的测定,结果令人满意。     

丁基罗丹明B—钼酸盐光度法连续测定铈和钪

在聚乙烯醇（ＰＶＡ）存在下，丁基罗丹明Ｂ（ＢＲＢ）分别与铈钼、钪钼杂多酸络阴离子形成离子缔合物，其最大吸收均位于５７０ｎｍ，表面摩尔吸光度分别为εＣｅ＝３．９６×１０＾６Ｌ．ｍｏｌ＾－１．ｃｍ＾－１，εＳｃ＝４．７１×１０＾５Ｌ．ｍｏｌ＾－１．ｃｍ＾－１，服从比耳定律范围分别为０－２４μｇ／Ｌ Ｃｅ和０－６０μｇ／ＬＳｃ，测定极限为Ｃｅ１．０μｇ／Ｌ（ｎ＝１２）和Ｓｃ１．９μｇ／Ｌ（ｎ＝１０），对     

流动注射化学发光测定盐酸土霉素

水浴加热后的盐酸土霉素在磷酸介质中,过氧化氢存在下与高碘酸钠反应产生强烈的化学发光。结合流动注射技术建立了一种测定盐酸土霉纱的化学发光新方法。方法的线性范围为１．０＊１０＾－８－６．０＊１０＾－６ｇ／ｍＬ盐酸土霉素。检出限为４．３＊１０＾－９ｇ／ｍＬ,ＲＳＤ为２．５％（Ｃｓ＝２．０＊１０＾－６ｇ／ｍＬ;ｎ＝１１）。     

脱氧核糖核酸（DNA）的极谱伏安行为研究

研究了脱氧核糖核酸的极谱伏安行为，在０．１ｍｏｌ．Ｌ＾－１ＮＨ４Ｃｌ溶液中ＤＮＡ产生一良好的极谱峰，峰电位Ｅｐ＝－１．６５Ｖ（ｖｓ．Ａｇ／ＡｇＣｌ），且峰电流ｉｐ与ＤＮＡ的浓度在４．５＊１０＾－５－３．７＊１０＾－４ｍｏｌ．ＬＯ＾－１范围内呈线性关系，可望用于ＤＮＡ的定量分析。     

用二安替比林对二乙氨基苯基甲烷和高碘酸钾催化光度法测定痕量钌

在磷酸介质和９０℃水浴条件下,Ｒｕ（Ⅲ）对高碘酸钾氧化二安替比林对二乙氨基苯基甲烷（ＤＡＥＡＭ）的显色反应强催化作用,建立了动力学光度法测定痕量钌的新方法。方法的线性范围为０－１．６μｇ／Ｌ＾－１和１．６－４．４μｇ．Ｌ＾－１;检出限为８．３４＊１０＾－８ｇ．Ｌ＾－１;对３μｇ．Ｌ＾－１Ｒｕ（Ⅲ）测定的ＲＳＤ为１．７９％（ｎ＝１１）本催化反应表观活化能为９１．６７ｋＪ．ｍｏｌ＾－１,表观速率常数为３．５３＊１０＾－３ｓ＾－１。考察了４０多种共存离子的影响,大多数常见离子干扰测定。方法用于矿样中痕量钌的测定,结果满意。     

鲁米诺—双氧水—铬（Ⅲ）化学发光体系测定化探样品中痕量砷

用鲁米诺－双氧水－铬（Ⅲ）化学发光体系结合巯基棉对Ａｓ（Ⅲ）的富集分离，建立了快速的测定化探样品中痕量砷的新方法，检测线性范围为１．０＊１０＾－４－１．０＊１０＾１ｍｇ／Ｌ，检出限为３．４＊１０＾－５ｍｇ／Ｌ。用于实际化探样吕测定，相对标准偏差为５．５＾－９．０％。     

聚邻苯二胺修饰电极抗坏血酸氧化酶生物传感器的研究

本文报道了聚邻苯二胺／抗坏血酸氧化酶生物传感器，用这种传感器测定人体血清中的抗坏血酸，线性范围在１．０×１０＾－４～２．５×１０＾－７ｍｏｌ／Ｌ之间，响应时间为７ｓ，检测限为１．０×１０＾－８ｍｏｌ／Ｌ。该传感器具有选择性好、灵敏度高和响应时间短等特点。     

一种基于形成杂多核络合物的荧光增敏效应的研究：Ⅲ.锰（Ⅱ）,钴（…

本研究了Ｍｎ＾２＋和Ｃｏ＾２＋对７－（８－羟基－３，６－二磺基萘偶氮）－８－羟基喹啉－５－磺酸－硼砂反应体系的混合荧光增敏作用。实验条件下，荧光增敏强度满足线性加和关系的范围是：Ｍｎ＾２＋浓度０￣２．９×１０＾－７ｍｏｌ／Ｌ；Ｃｏ＾２＋浓度０￣８．８～１０＾－７ｍｏｌ／Ｌ；总浓度不超过１．０×１０＾－６ｍｏｌ／Ｌ。检出限量为Ｍｎ＾２＋４．５×１０＾－９ｍｏｌ／Ｌ和Ｃｏ＾２＋１．４×１０＾－８ｍｏ     

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.