氢化物发生—缝管原子捕集—原子吸收法测定钢铁和地质试样中的砷

介绍简易的氢化物发生原子吸收测砷的方法，喷雾器负压将ＫＢＨ５吸入反应器，并将生成的ＡｓＨ３吸入乙炔－空气焰原子化。石英缝管使灵敏度提高３．５倍，方法的检测限为１．８ｎｇ／ｍＬ（５ｍＬ试样）。２０ｎｇ／ｍＬ Ａｓ（Ⅲ）标准液１０次测定的ＲＳＤ为３．８％。本法成功地应用于钢铁和地质标样中微量砷的测定。     

锆－7－碘－8－羟基喹啉－5－磺酸－EDTA－表面活性剂体系的荧光光度法研究

在ｐＨ６．２的ＨＡｃ－ＮａＡｃ缓冲溶液中，有溴化十六烷基三甲基铵（ＣＴＭＡ８）存在下，Ｚｒ（Ⅳ）与７－碘－８－羟基喹啉－５－磺酸（Ｈ＿２ＱＳＩ）及ＥＤＴＡ形成了四元荧光配合物。其组成为：Ｚｒ：Ｈ＿ＱＳＩ：ＥＤＴＡ：ＣＴＭＡＢ＝１：１：１：３。据此建立了错的选择性好、灵敏度高的荧光测定方法。方法检测限为１．２ｎｇ／ｍＬ。锆的线性范围为１．６ｎｇ～１．０μｇ／ｍＬ。用于铜合金中微量锆的测定，结果令人满意。     

THE RETENTION BEHAVIOR OF ARSENIC COMPOUNDS ON PRP-X100 COLUMN UNDER ALKALINE CONDITION

系统地研究了碱性条件下（ｐＨ８～１０．８）Ａｓ３＋，Ａｓ５＋，ＭＡ，ＤＭＡ和ＡＢ等砷化合物在ＰＲＰ－Ｘ１００阴离子交换柱上的保留行为。用火焰原子吸收光谱（ＦＡＡＳ）测定从ＨＰＬＣ分离的砷化合物，即通过一根１ｍ×０．２３ｍｍｉ．ｄ．不锈钢毛细管，将ＨＰＬＣ柱出口与ＦＡＡＳ的雾化器连接起来，采用乙炔／空气火焰，在１９３．７ｎｍ处测定。具体研究了两个流动相（２０ｍｍｏｌ／ＬＮＨ４ＨＣＯ３和２．５ｍｍｏｌ／Ｌ对－羟基苯甲酸－１．０ｍｍｏｌ／Ｌ苯甲酸水溶液），并系统研究了ｐＨ值和缓冲液浓度对上述５个砷化合物的保留时间的影响，发现对于２０ｍｍｏｌ／ＬＮＨ４ＨＣＯ３体系，在ｐＨ８．７时，ＡＢ，Ａｓ３＋，ＤＭＡ可以得到完全分离，通过梯度洗提（ｐＨ８．７到９．８，流速１．６５ｍＬ／ｍｉｎ），在１５ｍｉｎ内上述５个砷化合物可以得到良好分离；对于２．５ｍｍｏｌ／Ｌ对－羟基苯甲酸－１．０ｍｍｏｌ／Ｌ苯甲酸体系，在ｐＨ９．０及流速１．５ｍＬ／ｍｉｎ时，可以在１２ｍｉｎ内将上述５个砷化合物分离。     

新试剂5－氟偶氮胂Ⅰ荧光法测定铝的研究

本文报道了新试剂５－氟偶氮胂Ⅰ（５－ＦＡｓＡ－Ⅰ）的合成方法，研究了荧光光度法测定铝的反应条件。Ａｌ（Ⅲ）与试剂在ｐＨ５．６０ＨＡｃ－ＮａＡｃ缓冲介质中形成１＋１红色配合物并呈现荧光，λｅｘ／λｅｍ＝３４８．６／３９１．４ｎｍ，线性范围为０～０．２μｇ／ｍＬ，检测限为３．０ｎｇ／ｍＬ。用于分析茶叶样品中的铝，结果满意。     

同时测定食用植物油中抗氧剂叔丁基对羟基茴香醚和2，6－二叔丁基对甲酚的方法

报道了用高效液用色谱法同时测定食用植物油中的抗氧剂叔丁基对羟基茴香醚（ＢＨＡ）和２，６－二叔丁基对甲酚（ＢＨＴ）的实验方法。采用ＺｏｒｂａｘＯＤＳＣ_（１８）色谱住，甲醇：水（９０：１０，Ｖ／Ｖ）作流动相，检测波长为２４５ｎｍ，流速为１ｍＬ／ｍｉｎ。检测下限分别为１５ｎｇ（ＢＨＡ），９０ｎｇ（ＢＨＴ），回收率分别是９６．８％±９．８％（ＢＨＡ），９９．０％±３．２％（ＢＨＴ）。方法快速、准确，灵敏度高。     

用8－氨基喹啉高选择性分光光度法测定痕量锇的研究

研究了用８－氨基喹啉在ｐＨ３．６２的ＨＡｃ－ＮａＡｃ缓冲溶液中测定痕量Ｏｓ（Ⅳ）的分光光度法。常见的非贵金属和贵金属离子不干扰测定，并且选择性较好。Ｏｓ（Ⅳ）与８－氨基喹啉的组成比为１：３，表观摩尔吸光系数ε_（６００）＝１．３×１０~５Ｌ／ｍｏｌ·ｃｍ。在０～１０μｇ／１０ｍＬ范围内符合比耳定律。合成样品分析结果良好。     

同时测定食用植物油中抗氧剂叔丁基对羟基茴香醚和2，6－二叔丁基对甲酚的方法

 报道了用高效液用色谱法同时测定食用植物油中的抗氧剂叔丁基对羟基茴香醚（ＢＨＡ）和２，６－二叔丁基对甲酚（ＢＨＴ）的实验方法。采用ＺｏｒｂａｘＯＤＳＣ_（１８）色谱住，甲醇：水（９０：１０，Ｖ／Ｖ）作流动相，检测波长为２４５ｎｍ，流速为１ｍＬ／ｍｉｎ。检测下限分别为１５ｎｇ（ＢＨＡ），９０ｎｇ（ＢＨＴ），回收率分别是９６．８％±９．８％（ＢＨＡ），９９．０％±３．２％（ＢＨＴ）。方法快速、准确，灵敏度高。     

氢化物－原子吸收光谱法测定六味地黄丸中砷和锑

本文建立了氢化物原子吸收光谱法测定六味地黄丸中砷和锑的方法。方法的相对标准偏差砷为１．３％、锑为１．６％，回收率在９０％～１１０％之间，检出限分别为砷０．０６ｎｇ／ｍＬ、锑０．１ｎｇ／ｍＬ。本方法可用于中成药中砷和锑的测定。     

流动注射—氢化物发生—非色散原子荧光光谱法直接测定海水中的砷（Ⅲ）和砷（

用流动注射－氢化物发生－非色散原子荧光光谱法对海水中Ａｓ（Ⅲ）和Ａｓ（Ⅴ）的直接测定进行了研究,氢化物发生的最佳条件为：ＫＨＢ４溶液浓度为５ｇ．Ｌ＾－１（含ＫＯＨ５ｇ．Ｌ＾－１）,流速１０．０ｍＬ．ｍｉｎ＾－１;样品酸度为１．３ｍｏｌ．Ｌ＾－１ＨＣｌ,流速４．２ｍＬ．ｍｉｎ＾－１。对基体ＮａＣｌ,ＭｇＣｌ２,ＣａＣｌ２,Ｎａ２ＳＯ４以及微量共存金属离子（Ｃｄ,Ｚｎ,Ｐｄ,Ｃｕ）的干扰实验结果表明,基体和微量共存金属离子对Ａｓ（Ⅲ）的测定没有干扰。样品中Ａｓ（Ⅴ）的测定用硫脲进行预还原,通过总量和Ａｓ（Ⅲ）的含量的差减得到Ａｓ（Ⅴ）含量,在优化实验条件下下测量方法的检出限（３σ）为０．０８ｎｇ．ｍＬ＾－１;７次测定的相对标准偏差为０．４８％－１．３０％（８．０ｎｇ．ｍＬ＾－１标准溶液）。标准曲线和标准加入法对海水     

新体系Co－H_2O_2－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（Ａ＿０／Ａ）有良好线性关系。该指示反应灵敏度高选择性好，应用于维生素Ｂ＿（１２）和污水中钴的测定获得满意结果。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

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%).