磷钼杂多酸-L-半胱氨酸自组装超分子膜电极对亚硝酸根电催化还原的研究

制备了磷钼杂多酸－Ｌ－半胱氨酸自组装超分子膜电极（Ｐ２Ｍｏ１８－Ｌ－Ｃｙｓ／Ａｕ）。采用水平衰减全反射（ＡＴＲ－ＦＴＩＲ）光谱表征了膜的组成。研究了该膜电极的电化学性质，发现它在１．０ ｍｏｌ／Ｌ　Ｈ２ＳＯ４溶液中，于０．０～０．７Ｖ（ｖｓ．ＳＣＥ）间ＣＶ扫描出现两对稳定、可逆的氧化还原峰，其中峰电位分别为Ｅｍ１＝０．３３４ Ｖ，Ｅｍ２＝０．１８８Ｖ，对应着Ｐ２Ｍｏ１８Ｏ_(６２)~(６－)的两步２电子－２质子反应；计时库仑法计算了薄膜内的电子传递系数Ｄ为５．０１ × １０~（－８）ｃｍ２·ｓ～（－１）。该膜电极对酸性溶液中的ＮＯ_２~－有明显的电催化还原作用，初步探讨了电催化机理。用差分脉冲伏安法（ＤＰＶ）测定其还原峰电流与ＮＯ_２~－的浓度在２．０ ×１０~（－６）～２．０ × １０~（－４）ｍｏｌ／Ｌ范围内呈良好的线性关系，相关系数为０．９９５３，检测限５．０×１０~（－７）ｍｏｌ／Ｌ。该电极用于模拟水样中ＮＯ_２~－的测定，结果满意。     

基于亚硝化反应的极谱法测定亚硝酸根的研究

提出了一种基于在酸性介质中甲基紫与亚硝酸根发生亚硝化反应，极谱法测定亚硝酸根的新体系。亚硝化产物在－０．７５Ｖ（ｖｓ．ＳＣＥ）处２．５次微分波的波高与ＮＯ２－的质量浓度在２．０×１０－３～２．０×１０－２ｍｇ／Ｌ（Ｓ＝４μＡ），４．０×１０－３～１．６×１０－１ｍｇ／Ｌ（Ｓ＝０．０２ｍＡ）范围内成直线关系。该法重复性好，且大多数常见的阴、阳离子不干扰，用于污水中痕量ＮＯ２－的测定，结果满意。     

三核铁苯甲酸配合物［Fe_3O（OBz）_6（CH_3OH）_3］（NO_3）（

测定了三核苯甲酸铁配合物［Ｆｅ_３Ｏ（ＯＢｚ）_６（ＣＨ_３ＯＨ）_３］（ＮＯ_３）（ＣＨ_３ＯＨ）_２（ＯＢｚ~－＝苯甲酸根）的电子光谱，应用配体场理论和Ｔ－Ｓ图求得配体场参数１０Ｄｑ＝１２４５７ｃｍ~（－１）。用ＣＮＤＯ／２方法对其简化模型进行了计算。     

溴酸钾氧化靛红催化光度法测定痕量亚硝酸根

基于磷酸介质中ＮＯ２＾－催化溴酸钾氧化靛红的褪色反应，建立了测定痕量ＮＯ２＾－的新方法，并讨论了其动力学条件。方法检测限为１．３６×１０＾－６ｇ／Ｌ，线性范围０．３￣２μｇ／２５ｍＬ，方法简便，已用于环境水样中痕量ＮＯ２＾－的测定。     

示波极谱法测定内燃机车冷却液中亚硝酸根含量

采用ＪＰ３－１型示波极谱仪，滴东电极１．５次微分，在－０．６～－１．９０Ｖ范围内，通过对多种底液组分的试验，确定了在２．００×１０＾－３ｍｏｌ．Ｌ＾－１Ｍｎ＾２＋，盐酸（ｐＨ２）底液中，ＮＯ＾－２在－１．３２Ｖ（ｖｓ．ＳＣＥ）处于生极谱法，ＮＯ２浓度在４．００×１０＾－５～４．００×１０＾－３ｍｏｌ．Ｌ＾－１范围与峰高呈线性关系。方法可用于测定内燃机车冷却液中ＮＯ２含量，其选择性好，操作简便，快速     

亚硝酸根—巯基乙酸—钴（Ⅱ）络合物的极谱吸附波研究

提出了一个测定痕量亚硝酸根的极谱吸附波新体系．在含有巯基乙酸（ＴＧＡ）和钻．（Ⅱ）的 ｐＨ ４．４的 Ｈ２ＳＯ４－ＮａＡｃ介质中，得到一灵敏的亚硝酸根络合物单扫极谱吸附波，峰电位为－０．７５ Ｖ（ｖｓ．ＳＣＥ）．峰电位与亚硝酸根浓度在１．１× １０－３－８．７×１０－６ｍｏｌ／Ｌ范围内呈线性关系．检出限为 ５． ５×１０－９ ｍｏｌ／Ｌ．本法简便快速，选择性好，用于水样和食品中痕量ＮＯ-２的测定，结果满意。     

CaO-SiO2-Al2O3-MgO-TiOx-FeOy体系氧化动力学

用电动势和化学分析方法研究了富钛还原熔渣－ＣａＯ－ＳｉＯ_２－Ａｌ_２Ｏ_３－ＭｇＯ－ＴｉＯ_ｘ－ＦｅＯ_ｙ体系的氧化动力学,得出了氧在熔渣中的扩散速率常数分别为 ０． ６６×１０~（－５） ｍ· ｓ~（－１）和 １． ９８×１０~（－５） ｍ·ｓ~（－１）,研究表明：固体电解质构成的氧浓差电池法得出的结果不仅可靠,且方法快速、简便．     

利用微波消解和高效液相色谱荧光检测法测定环境水样中痕量硒

基于微波消解和正相液相色谱－荧光检测测硒法,实现了对环境水样中亚纳克级硒的测定。考察了ＨＮＯ３和Ｈ２ＳＯ４－Ｈ２Ｏ２两种消化体系及其工作条件,方法检出限分别可达 ７．２和 １０．４ ｐｇ Ｓｅ,对标准参考物质的回收率分别为９９．４±２．０和９７．８±２．５％,在０～１．５ｎｇＳｅ范围内有线性关系（Ｒ２＜０．９９６）。对北京地区 ４种不同类型水体水样含硒量进行了分析测定（２ｍＬ样品）,其浓度范围为 ０．２０～０．９０μｇ／Ｌ,标准加入回收率为９９．１％～１０３．４％。     

病人血样中痕量锗,锶的石墨炉原子吸收光谱法测定

本文运用石墨炉ＡＡＳ法加基体改进技术，测定了５０岁以上病人血清及环境水样中锗和锶的含量。用０．０１ｍｏｌ／ＬＨＮＯ３－０．１％ＴｒｉｔｏｎＸ－１００稀释血清，测定精度可与火焰法媲美。锗，锶的特征量分别为２８ｐｇ和１８ｐｇ；线性范围为０－２５０ｎｇ／ｍＬ和－３５．０ｎｇ／ｍＬ；相对标准偏差（ｎ＝１０）４．１０％和２．４９％；回收率分别为９２．２％－９９．０％和９２．０％１０２％。方法快速准确，结果满     

偶合化学发光法测定血清中亚硝酸盐

采用正交试验法建立了Ｌｕｍｉｎｏｌ－ＮＯ－２－Ｋ４［Ｆｅ（ＣＮ）６］偶合发光体系测定血清ＮＯ－２的方法。本法测定ＮＯ－２的线性范围为９．０×１０－６～１．０×１０－３μｇ／Ｌ,检出限３．５×１０－６μｇ／Ｌ。对１．０×１０－４μｇ／ＬＮＯ－２连续测定１１次的相对标准偏差为２．３％。用于血清中亚硝酸根的测定,结果满意。     

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.     

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.     

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.