共沉淀分离富集—ICP-AES法测定高纯钨酸钠中痕量铍钪镱锌

以Ｌａ（ＯＨ）３为共沉淀剂，使高纯Ｎａ２ＷＯ４中痕量Ｂｅ，Ｓｃ，Ｙｂ，Ｚｎ与基体相分离并富集，然后用ＩＣＰ－ＡＥＳ法测定，实验表明，发ＰＨ为１２时，用６ｍＬ％１％Ｌａ溶液进行两次共沉淀淀分离能使上述元素定量分离回收，回收率为９２．７％－１０２．５％，相对标准偏差为２．８－５．９％。     

微晶萘固液萃取分离和ICP-AES测定痕量金的研究

在一定酸度的盐酸介质中,络阴离子ＡｕＣｌ－４与孔雀绿（ＭＧ）形成稳定的离子缔合物,可被析出的微晶萘定量吸附,实现痕量金的分离与富集。分离了基体富集物中的Ａｕ,并用ＩＣＰ－ＡＥＳ测定。详细考察了影响金的分离与测定的各种因素。在优化的实验条件下,方法的检出限为６．０ｎｇ／ｍＬ,ＲＳＤ为１．３４％（ｎ＝９）。本法已用于矿石浸取液和标准矿样中痕量金的测定,分析结果满意。     

液膜富集分光光度法测定水中痕量铬（Ⅵ）

本文研究了分离，富集Ｃｒ（Ⅵ）的最佳液膜组成和实验条件，确立了兰１１３Ｂ－ＴＯＡ－煤油－液体石蜡－ＮａＯＨ液膜体系。用本法富集，测定工业废水中的Ｃｒ（Ⅵ），富集倍数达７５，相对标准偏差为１．１％，回收率９９％以上。     

Nafion修饰金电极阳极溶出伏安法测定痕量碲

本文用Ｎａｆｉｏｎ修饰金盘电极，在０．０４ｍｏｌ／ＬＬｉＣｌ和ＰＨ２的Ｈ２ＳＯ４底液中，阳极溶出伏安法测定痕量碲，研究了富集溶出过程的特性和优化条件，碲浓度在０．２－１５ｎｇ／ｍＬ范围内与溶出峰电流呈良好的线性关系。本法灵敏度高，选择性好，用于测定小麦粉和玉米粉中痕量碲，测定标准偏差小于０．０７μｇ／ｇ，与ＩＣＰ测定结果比较其相对误差小于１６％。     

用ICP—AES研究茶碱负载树脂对银离子的吸附行为

采用浸渍法将茶碱负载子阳离子交换树脂上,制得茶碱负载树脂（ＴＣＲ）。在一定浓度的硝酸或氨水溶液中,茶碱负载树脂具有较好的化学稳定性。以ＩＣＰ－ＡＥＳ作为检测手段,考察了其对银离子的吸附性能。结果表明,ＴＣＲ在ｐＨ４～７范围内可定量吸附Ａｇ＾＋,２ｍｇ／ｍＬ硫脲－０．５ｍｏｌ／Ｌ ＨＮＯ３的混合溶液可作为银的良好解吸剂。该负载树脂对银的吸附容量大,选择性好,适用于痕量银的富集分离。     

偶合反应化学发光法测定痕量银的研究

本将Ａｇ（Ⅰ）催化Ｓ２Ｏ＾２－８氧化Ｍｎ（Ⅱ）生成ＭｎＯ＾－４的催化反应与ＬｕｍｉｎｏｌＭｎＯ＾－４－ＯＨ＾－的化学发光反应相偶合，建立起一种新的灵敏测定痕量银的化学发光分析法，在所研究的优化条件下，该法测定银的选择性较好，检测限达到３．２×１０＾－１２ｇ／ｍＬＡｇ线性浓度范围为１．０×１０＾－１１－１．０×１０＾－５ｇ／ｍＬＡｇ，用于水样分析，结果较为满意。     

微波溶样ICP-MS直接测定茶叶中15种痕量稀土元素

本文报道用ＨＮＯ３－Ｈ２Ｏ２微波溶样，不经分离富集，用标准加入ＩＣＰ－ＭＳ法，直接测定茶叶中１５种痕量稀土元素．对微波溶样和等离子体质谱测定条件进行了优化选择．在最佳实验条件下，用本法测定了国家一级茶叶标准物质ＧＢＷ０７６０５中的单一稀土元素，测得值与标准值很好吻合     

固载硫杂杯芳烃树脂分离富集-火焰原子吸收法测定痕置银

报道了色谱301固载硫杂杯芳烃树脂分离预富集-火焰原子吸收光谱法测定痕量银的新方法。探讨了固载硫杂杯芳烃树脂对银的吸附原理与最佳条件。将含Ag^＋试液在pH=10、温度为23±2℃的条件下恒温震荡10min，静置10min，Ag^＋可被树脂定量富集被吸附的Ag^＋可用5mL酸性硫脲（0．15mol／L HCl＋0．15mol／L硫脲）完全洗脱，洗脱液中的银用火焰原子吸收光谱法测定。该法对银的检出限为0．17μg／L（3σ，n=11）；线性范围为0．006—3mg／L。对0．18mg／L的Ag^＋标液进行7次测定，RSD=1．53％。回收率在99．9％-105．0％之间。用于“二次资源”锌矿渣和环境水样中痕量银的测定，结果满意。     

双载体液膜分离富集痕量汞和锰

１　引　言由于乳状液膜技术具有高效，快速、简便等优点，被广泛地应用在痕量金属元素的分离和富集中。现有的报道主要是采用单载体液膜体系对痕量金属元素进行预富集，本文则采用混合双载体的新液膜体系实现了痕量汞和锰的同时富集和分离，用化学破乳法进行破乳，结合电感耦合等离子体原子发射光谱法进行测定，得到了比较满意的结果。２　实验部分２．１　仪器与试剂　ＰＬＡＳＭＡ－（Ⅰ）电感耦合等离子体原子发射光谱仪，提取器，电动搅拌机。Ｈｇ、Ｍｎ标准溶液按常规方法配制。Ｓｐａｎ８０，Ｐ２０４［二－（２－乙基己基）膦酸］，…     

化学分离－质谱法定量分析高纯Dy_2O_3中稀土杂质

以Ｐ_（５０７）萃淋树脂为固定相，ＨＣｌ－ＮＨ４Ｃｌ为淋洗液，研究了９９．９９９％～９９．９９９９％高纯Ｄｙ２Ｏ３中痕量稀土与基体Ｄｙ的分离法，以及火花源质谱法的测定条件。可分析９９．９９９９％超高纯Ｄｙ２Ｏ３中痕量稀土杂质，测定限０．００１～０．１×１０－６，误差３０％。     

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.     

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.     

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.     

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%).     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

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.