Mo(W)-Cu(Ag)-S原子簇化合物的研究现状

本文在研究Ｍｏ（Ｗ）－Ｃｕ（Ａｇ）－Ｓ原子簇化合物的低热固态合成化学基础上，详细地对该类簇合物进行了归纳，从中提出；１，ＭＯ４－ｎＳｎ＾２＾－（Ｍ＝Ｍｏ，Ｗ；ｎ＝２，３，４）作为配体中心。２，氧原子在簇合物中仅作为端基，不参与同其他金属成键。３，单个ＭＳ４（Ｍ＝Ｍｏ，Ｗ）基团最多只能键合六个Ｃｕ（Ａｇ）原子，即最大核数为七。４，迄今为止所有Ｍｏ（Ｗ）－Ｃｕ－Ｓ原子簇化合物中Ｃｕ均为＋１价。５，预计     

ErCl_3－MgCl_2－LiCl三元体系的液相限

ＥｒＣｌ＿３－ＭｇＣｌ＿２－ＬｉＣｌ三元体系的液相限彭绍琴，郑朝贵（北京大学化学系北京１００８７１）关键词ＥｒＣｌ＿３，ＥｒＣｌ＿３－ＭｇＣｌ＿２－ＬｉＣｌ三元体系，相图研究稀土熔盐相图对于了解稀土化合物的基本物理化学性质，从已知相图提取热力学数据，...     

溶剂化金属原子浸渍法制备的Ni－Ag／γ－Al_2O_3催化剂的结构表征

应用溶剂化金属原子浸渍（ＳＭＡＩ）法和普通浸渍（ＣＩ）法制备了三种不同摩尔比的γ－Ａｌ２Ｏ３负载Ｎｉ－Ａｇ双金属催化剂。ＸＲＤ和磁测定结果表明ＳＭＡＩ催化剂中Ｎｉ和Ａｇ的粒度均小于金属含量相同的ＣＩ催化剂，ＳＭＡＩ催化剂中Ｎｉ和Ａｇ未形成合金，而ＣＩ催化剂中Ｎｉ和Ａｇ形成了合金。ＳＭＡＩ和ＣＩ催化剂都具有超顺磁性。ＸＰＳ测定结果表明ＳＭＡＩ催化剂中零价Ｎｉ和Ａｇ的含量均高于ＣＩ催化剂。ＳＭＡＩ催化剂Ｎｉ在表面含量高于体相，Ｎｉ在表面富集，而ＣＩ催化剂Ｎｉ在表面和体相的含量相同     

磷酸三丁酯色层分离—电感耦合等离子体原子发射光谱法测定U3Si2

本法对Ｕ３Ｓｉ中２２个微量杂质元素的测定，进行了较系统的实验研究，取样１００ｍｇ时，Ａｌ、Ｃａ、Ｃｄ、Ｃｒ、Ｃｕ、Ｆｅ、Ｈｆ、Ｉｎ、Ｍｇ、Ｍｎ、Ｍｏ、Ｎｂ、Ｎｉ、Ｐｂ、Ｓｎ、Ｔａ、Ｔｉ、Ｖ、Ｙ、Ｚｎ和Ｚｒ的测定范围５μｇ／ｇ－８００μｇ／ｇ，回收率为９４％－１０５％，ＲＳＤ（ｎ＝８）０．４％－１．２％。     

Mo（W）－Cu（Ag）－S原子簇化合物的研究现状

本文在研究Ｍｏ（Ｗ）－Ｃｕ（Ａｇ）－Ｓ原子簇化合物的低热固态合成化学基础上，详细地对该类簇合物进行了归纳，从中提出：１．（Ｍ＝Ｍｏ，Ｗ；ｎ＝２，３，４）作为配体中心．２．氧原子在簇合物中仅作为端基，不参与同其他金属成键．３．单个ＭＳ４（Ｍ＝Ｍｏ，Ｗ）基团最多只能键合六个Ｃｕ（Ａｇ）原子，即最大核数为七．４．迄今为止所有Ｍｏ（Ｗ）－Ｃｕ－Ｓ原子簇化合物中Ｃｕ均为＋１价．５．预计合低价态Ｍｏ（Ｗ）的这类簇合物将会有很大进展．     

Ni－Cu和MgO－SiO_2间的相互作用及其对催化性能的影响

本文用ＴＰＲ，ＩＲ，ＴＰＤ和ＴＰＳＲ等技术研究了以表面改性法制备的ＭｇＯ－ＳｉＯ２（ＭＳＯ）表面复合物担载的Ｎｉ－ＣＵ合金间的相互作用及其对ＣＯ加氢反应催化性能的影响．结果表明，ＮｉＯ－ＣｕＯ与ＭＳＯ间的相互作用导致部分ＭＯ与ＭＳＯ形成表面物种从而使金属组分氧化物还原温度明显升高；还原后的Ｎｉ－Ｃｕ／ＭＳＯ表面上存在着两类活性中心，即合金相中的Ｎｉ与载体相中的Ｍｇ２＋（或Ｍｇ２＋－Ｏ）；在两类活性中心的协同作用下，ＣＯ吸附除有孪生、线式和桥式吸附态物种外，还有一种新的卧式吸附态（Ｎｉ．．．Ｃ＝Ｏ→Ｍｇ２＋）．这种吸附态的活化程度较高，易在表面上发生裂解形成Ｎｉ－Ｃ和Ｍｇ２＋－Ｏ，其中Ｎｉ－Ｃ是加氢反应的碳源；Ｈ２在催化剂表面上发生解离吸附形成Ｎｉ－Ｈ和Ｍｇ２＋－ＯＨ，前者比较活泼，是加氢反应的氢原．ＣＯ加氢生成烃类的反应在Ｎｉ中心上按＂表面碳＂机理进行，其生成ＣＺＨ４的选择性高于８０％；Ｈ２Ｏ的生成反应按２（Ｍｇ２＋－ＯＨ）－→Ｍｇ２＋＋（Ｍｇ２＋－Ｏ）＋Ｈ２Ｏ方式进行．     

YbCl_3－CaCl_2－MgCl_2三元体系液相限的研究

借助于ＤＴＡ测定了ＹｂＣｌ３－ＣａＣｌ２－ＭｇＣｌ２三元体系液相限．发现本体系有对应于ＹｂＣｌ３、ＣａＣｌ２、ＭｇＣｌ２和不稳定化合物Ｘ的四个液相面，五条二次结晶线，一个三元低共熔点Ｅ（３８．０ｗｔ％ＹｂＣｌ３，３１．０ｗｔ％ＣａＣｌ２，３１．０ｗｔ％ＭｇＣｌ２；５５６℃）和三元转熔点Ｐ’（４５．５ｗｔ％ＹｂＣｌ３，２８．０ｗｔ％ＣａＣｌ２，２６．５ｗｔ％ＭｇＣｌ２；６００℃）．     

SMAI和CI法制备的Ni—Ag／SiO2催化剂的结构与催化性质研究

应用溶剂化金属原子浸渍（ＳＭＡＩ）法和普通浸渍（ＣＩ）法制备了金属含量相同的ＳｉＯ２负载Ｎｉ－Ａｇ双金属催化剂。ＸＲＤ和磁测定结果表明ＳＭＡＩ催化剂中Ｎｉ和Ａｇ的粒度均小于金属含量相同的ＣＩ催化剂，ＳＭＡＩ催化剂中Ｎｉ和Ａｇ未形成合金，而ＣＩ催化剂中Ｎｉ和Ａｇ形成了合金。ＳＭＡＩ和ＣＩ催化剂都具有超顺磁性。研究了这些催化剂在甲苯加氢反应的催化性质，结果表明与组成相同的普通浸渍法催化相比，ＳＭＡＩ催     

α－石英表面自由基和离体肺泡巨噬细胞内游离Ca~（2＋）、Mg~（2＋）浓度的关系

本文用ＡＲ－ＣＭ－ＭＩＣ阳离子测定系统及Ｆｕｒａ－２荧光技术，研究了研磨后表面存在自由基的α－石英，和离体肺泡巨噬细胞作用后细胞内游离Ｃａ２＋浓度（［Ｃａ２＋］）和游离Ｍｇ２＋浓度（［Ｍｇ２＋］ｉ）的关系．发现在含Ｃａ２＋和Ｍｇ２＋的介质中，α－石英表面自由基越多，［Ｃａ２＋］ｉ和［Ｍｇ２＋］ｉ升高越大；在无Ｃａ２＋和Ｍｇ２＋的介质中，新研磨的α－石英能引起［Ｃａ２＋］ｉ和［Ｍｇ２＋］ｉ升高．Ｃａ２＋和Ｍｇ２＋的升高可能部分由于细胞内结合钙和结合镁的释放．     

甲醇在催化剂MgO（100）面上吸附的量子化学研究

本文用ＣＮＤＯ／２半经验最子化学计算方法对ＣＨ３ＯＨ分子在（ＭｇＯ）４（１００）面上的２８种可能的吸附态进行了优化计算，得到以ＣＨ３ＯＨ分子中－ＣＨ３取向吸附在（ＭｇＯ）４（１００）面的Ｏ＾－原子上，且为重叠式构型最稳态。此构型中由于－ＣＨ３上的三个氢原子形成结构适应的三氢正电集团与氧的静电作用的结果。从吸附态的能量及Ｍｕｌｌｉｋｅｎ集居数上分析得甲醇在ＭｇＯ催化剂上有利于形成ＣＨ４和ＣＯ，这一结     

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.     

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.     

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.