TiO2调变对MoO3／γ—Al2O3和CoO—MoO3／γ—Al2O3催化性能的影响

采用气相流动吸附法制备ＴｉＯ２／γ－Ａｌ２Ｏ３复合载体，用浸渍法其担载一定量的ＭｏＯ３或ＣｏＯ－ＭｏＯ３。用ＸＲＤ、ＬＲＳ和ＴＰＲ等技术，考察了Ｍｏ或Ｃｏ－Ｍｏ催化剂的表面结构和还原性能，并有和中压固定床反应装置测定催化剂的噻吩加氢脱硫和环己烯加氢的活性。     

Co-Mo/TiO2和Co-Mo/γ-Al2O3加氢脱硫催化剂的研究

本文考察了ＣｏＭｏ／ＴｉＯ２和ＣｏＭｏ／γ－Ａｌ２Ｏ３催化剂的加氢脱硫性能及表面结构变化和处理条件对其活性的影响，担体ＴｉＯ２（Ａ）和ＴｉＯ２（Ｂ）分别采用ＴｉＯＳＯ４水解法制备，结果表明，催化剂的活性顺序为ＣｏＭｏ／ＴｉＯ２（Ａ）＞ＣｏＭｏ／ＴｉＯ２（Ｂ）＞ＣｏＭｏ／γ－Ａｌ２Ｏ３，催化剂的预处理条件对催化剂的加氢脱硫和加氢活性有很大影响，ＴｉＯ２担体上Ｍｏ物种主要以八面体配位构型存在，Ｍｏ＾－     

炭担载的Mo和CoMo加氢脱硫催化剂

用仲钼酸铵和酸钴水溶液浸渍方法将ＭｏＯ３和ＣｏＯ担载在少在性炭担体上，制成Ｍｏ／Ｃ和ＣｏＭｏ／Ｃ催化剂。运用ＤＴＡ，ＸＰＳ，ＦＴ－ＬＲＳ等手段考察了ＭｎＯ３在活性炭担体表面的分散状态及Ｈ２还原能力随ＭｏＯ３含量的变化，并在中压固定床反应装置上测定了催化剂的噻吩加氢脱硫和环己烯加氢反应活性。     

再生处理过程对NiMo/γ-Al_2O_3工业催化剂结构及加氢性能的影响

ＮｉＭｏ／γ－Ａｌ２Ｏ３是石油加工过程中广泛采用的加氢催化剂，有关这类催化剂的制备、结构、催化机理等都进行过深入的研究［１，９，１０］．近年来，由于环境保护的要求日益严格，失活催化剂的处理已成为突出的问题，因此失活的加氢催化剂的再生利用已引起了工业界...     

MoO＿3／（TiO＿2－SiO＿2）催化剂的表面分散状态及催化性能的研究

用气相流动吸附法（ｇｒａｆｔｉｎｇ）制备复合载体，用浸渍法（ｉｍｐｒｅｇｎａｔｉｏｎ）制备ＭｏＯ３／（ＴｉＯ２－ＳｉＯ２）催化剂．应用ＬＲＳ和ＴＰＲ技术研究ＭｏＯ３在复合载体ＴｉＯ２－ＳｉＯ２表面的分散状态，发现ＴｉＯ２在ＳｉＯ２表面的分散可增强ＭｏＯ３与载体之间的相互作用，提高ＭｏＯ３在载体表面的分散阈值．催化剂的活性评价在固定床中压反应装置中进行，以６９％（ｗｔ）环己烷、２０％（ｗｔ）的环己烯、１０％（ｗｔ）的苯、１％（ｗｔ）的噻吩混合液为反应液，以噻吩、环己烯和苯的转化率作为催化剂的ＨＤＳ、ＨＹＤ、ＢＨＤ活性指标．结果表明，经ＴｉＯ２调变后，其ＨＤＳ、ＨＹＤ、ＢＨＤ活性都较原来高，对于不同ＭｏＯ３含量的ＭｏＯ３／（ＴｉＯ２－ＳｉＯ２），ＨＤＳ、ＨＹＤ催化性能测试发现，当ＭｏＯ３含量低于分散阈值时，其ＨＤＳ、ＨＹＤ活性随ＭｏＯ３含量线性上升，但在高于分散阈值后，几乎保持不变．该催化剂对苯几乎没有加氢活性，显示出很高的环己烯加氢选择性．通过分散阈值与其ＨＤＳ、ＨＹＤ活性的关系可知，分散阈值可作为优化加氢精制催化剂配比的一个重要参数，具有较强的实际意义     

活性炭为载体加氢脱氮催化剂的研究

Ｍｏ／Ｃ、Ｎｉ／Ｃ和Ｎｉ－Ｍｏ／Ｃ催化剂吡啶加氢脱氮研究表明，Ｍｏ／Ｃ催化剂在Ｍｏ含量小于３．６５％时，随着Ｍｏ含量的增加，脱氮活性增加，其后趋于稳定。Ｎｉ／Ｃ催化剂也具有加氢脱氮活性，在Ｎｉ含量为５％左右达到最大值。Ｎｉ－Ｍｏ／Ｃ催化剂只有在Ｎｉ和Ｍｏ相互匹配时才具有较高的活性。ＸＰＳ的研究表明，硫化后Ｎｉ－Ｍｏ／Ｃ催化剂的Ｍｏ主要是以ＭｏＳ２的模型存在的；Ｎｉ是以ＮｉＳ和Ｎｉ３Ｓ２的混合生存在     

Co－Mo／TiO_2和C0－M0／γ－Al_2O_3加氢脱硫催化剂的研究

本文考察了ＣｏＭｏ／ＴｉＯ３和ＣｏＭｏ／γ－Ａｌ２Ｏ３催化剂的加氢脱硫性能及表面结构变化和预处理条件对其活性的影响．担体ＴｉＯ２（Ａ）和ＴｉＯ２（Ｂ）分别采用ＴｉＣｌ４中和法和ＴｉＯＳＯ４水解法制备．结果表明，催化剂的活性顺序为ＣｏＭｏ／ＴｉＯ２（Ａ）＞ＣｏＭｏ／ＴｉＯ２（Ｂ）＞ＣｏＭｏ／γ－Ａｌ２Ｏ３催化剂的预处理条件对催化剂的加氢脱硫（ＨＤＳ）和加氢（ＨＹＤ）活性有很大影响，ＴｉＯ２担体上Ｍｏ物种主要以八面体配位构型存在，Ｍｏ６＋更易于还原成低价态．     

Co—Mo／C催化剂的O2吸附研究

浸渍法制备了一系列不同浸渍顺序，金属含量和Ｍｏ前区体的Ｃｏ／Ｍｏ／Ｃ催化剂并用脉冲色谱法测定了催化剂的Ｏ２吸附量，考察了催化剂制备，金属担载量，预处理条件，Ｏ２吸附温度，Ａｒ吸扫温度等参数对Ｏ２吸附量的影响。常压微型反应器上测定了催化剂的噻吩加氢脱硫活性。     

超细Mo／Al_2O_3催化剂（Ⅰ）──催化及还原性质研究

研究两种不同制备方法──浸渍法和超临界流体干燥法制得的超细Ｍｏ／Ａｌ２Ｏ３催化剂的加氢与加氢脱硫催化性质及还原性质，并与以普通Ａｌ２Ｏ３作载体制得的Ｍｏ／Ａｌ２Ｏ３催化剂相比较．结果表明，超细粒子催化剂催化性质较大程度地受制备方法的影响．ＴＰＲ、ＸＲＤ、ＬＲＳ分析结果表明，超细氧化铝载体和超临界流体干燥法的使用均有利于Ｍｏ在Ａｌ２Ｏ３表面的分散．     

超细Mo／Al2O3催化剂（II）：加氢脱硫表面结构性质研究

利用ＸＰＳ考察了超细Ｍｏ／Ａｌ２Ｏ３的氧化态反应后的表面结构性质，结果表明，氧化态催化剂中Ｍｏ主要以Ｍｏ＾６＾＋形式存在，而反应后则以Ｍｏ＾６＾＋和Ｍｏ＾４＾＋两种价态共存，硫亦存在－２及＋６两种价态，不同价态Ｍｏ，Ｓ物种存在的比例受催化剂Ｍｏ含量及制备方法的影响。Ｍｏ含量增加，Ｍｏ＾６＾＋所占的比例逐渐减小，Ｍｏ＾４＾＋所占比例逐渐增加，Ｓ＾６＾＋所占的比例膛渐减小，Ｍｏ＾４＾＋所占比例逐渐增加     

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.     

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.     

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%).     

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.