四苯硼钠试剂纯度的测定

我们发现四苯硼离子能与碱性有机染料——三苯甲烷类的孔雀绿、溴酚蓝等和罗丹明类的丁基罗丹明B等的阳离子生成有色络合物,它们的吸收光谱与其相应的溅性有机染料不同,可以利用这类反应来测定四苯硼离子,本文研究了孔雀绿与四苯硼离子形成络合物的条件和组成及其光度性质。     

催化比色法测定矿物中的微量锰(锰—孔雀绿—高碘酸钾体系)

深沢力等人研究了锰离子催化高碘酸钾氧化孔雀绿退色反应。当pH值与温度增加时,反应速度加快。确定pH为3.8,温度31℃为反应条件。铝离子、铁离子干扰用氟离子掩蔽,制定了高纯硅中痕量锰检测方法。     

硼—姜黄素络合物的高效液相色谱研究及应用

本文研究了在非水本系中硼与质子化的姜黄素形成的络合物以无水甲醇为溶剂，在Ｃ１８色谱柱上用甲醇－水（８０：２０Ｖ／Ｖ）作流动相分离并检测，硼的校正曲线线性范围为０．４－３．２μｇ／２５ｍＬ，硼的校测限为０．０８ｎｇ。此法用于复合硼肥的分析，结果令人满意。     

离子对高效液相色谱—TPPS4光度法测定痕量锌和铜

本文用ＴＰＰＳ４作柱前衍生试剂，研究了试剂与锌和铜的配位反应，在ＯＤＳ柱上，用乙腈／水体系作流动相，苄基三乙基氯化铵作离子对试剂，在４１５ｎｍ处检测，提出了离子对高效液相色谱－光度法快速分离测定痕量锌铜的新方法，检测限：Ｚｎ和Ｃｕ分别为０．１５和０．１０ｎｇ／ｍＬ，本法用于花生样品中痕量Ｚｎ，Ｃｕ的测定。结果与ＡＡＳ一致。     

镍电极开路电位测定微量硼氢根离子

实验采用循环伏安法，用镍电极代替铂铑等贵金属电极测定了碱性体系中不同硼氢根离子浓度下的开路电位，得出了研究电极的开路电位（-0．355～-0．280vs.SCE／V）与微量硼氢根离子浓度的对应关系，并用于监测电解偏硼酸钠制备硼氢化钠体系中微量硼氢根离子，同时计算了该方法的误差。结果表明，测量结果的相对标准偏差为2．2％；回收率为98．4％。该法简单、快速，可测定10^-5～10^-3mol／L范围的硼氢根离子浓度。     

催化动力学光度法测定痕量钯

基于乙酸－乙酸钠缓冲溶液（ｐＨ４．７５）中，痕量钯（Ⅱ）催化次磷酸钠还原孔雀绿褪色的反应，研究了反应的最优化条件和动力学参数，建立了一种灵敏度高、选择性好的痕量钯的催化动力学光度分析新方法。方法的检测限为２。２７３×１０＾－７ｇ／Ｌ，线性范围０．１￣０．８μｇ／２５ｍＬ，方法应用于模拟合金试样的测定，取得满意的结果。     

金属离子与卟啉的嵌入反应动力学研究──Ⅶ．一元酸根催化Cu(Ⅱ)与溴化间－四(N－乙酸甲酯基－3－吡啶基)卟啉的配位反应

研究了在３５±０．１℃、离子强度０．５ｍｏｌ／Ｌ（ＫＣｌ）条件下，甲酸根、乙酸根、丙酸根和丁酸根分别催化Ｃｕ（Ⅱ）离子与四溴化间－四（Ｎ－乙酸甲酯基－３－吡啶基）卟啉（Ｈ２Ｔβ－Ｎ－ＡＣＭｓｐｙＰＢｒ４）的反应动力学及其机理，该类反应对卟啉和Ｃｕ（Ⅱ）离子均为一级反应，反应动力学方程为：ｄ［ＣｕＰ＾４＋］／ｄｔ＝ｋ｛１．０＋ｂ［Ａ＾－］）／（１．０＋Ｋ３，４．［Ｈ＾＋］＾２｝［Ｃｕ＾２＋］［Ｐ］Ｔ     

溴酸钾—碘离子体系催化动力学电位法测定痕量铜

以ＫＢｒＯ３氧化Ｉ＾－的反应为指示反应，用碘离子选择电极跟踪Ｉ＾－。在适宜条件下，该指示反应为一级反应。反应速度可用电位的变化ΔＥ表示。当时间固定，ΔＥ与铜浓度在０￣３ｍｇ／Ｌ范围内呈线性关系，检出限为０．２μｇ／Ｌ。该方法已成功地用于土豆和红薯中痕量铜的测定。     

离子对高效液相色谱－TPPS＿4光度法测定痕量锌和铜

本文用ＴＰＰＳ＿４作柱前衍生试剂，研究了试剂与锌（Ⅱ）和铜（Ⅱ）的配位反应，在ＯＤＳ柱上，用乙腈／水体系（２８％，Ｖ／Ｖ）作流动相，苄基三乙基氯化铵作离子对试剂．在４１５ｎｍ处检测，提出了离子对高效液相色谱。光度法快速分离测定痕量锌铜的新方法，检测限：Ｚｎ和Ｃｕ分别为０．１５和０．１０ｎｇ／ｍＬ，本法用于花生样品中痕量Ｚｎ、Ｃｕ的测定，结果与ＡＡＳ一致。     

注入热焓法测定萃取磷酸中三氧化硫

以钡离子与硫酸根离子沉淀反应的热效应为基础，通过测定孤立体系中的温度变化，建立了测定萃取磷酸中三氧化硫的注入热焓法，该法在４．０－３２．０ｇ／Ｌ范围内可准确测定ＳＯ３的含量，相对标准偏差为１．８％；标准加入回收率为９８％－１０３％。     

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.     

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.     

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.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

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.