CO2在受主掺杂CaTiO3体系甲烷氧化偶联反应中的作用

本文采用了ＣＯ２程度升温脱附（ＣＯ２－ＴＰＤ）、ＣＯ２分步热脱附（ＣＯ２－ＳＴＤ）、ＣＯ２气氛中电导测量和ＣＯ２作为甲烷氧化偶联反应（ＯＣＭ）烯释气等方法，研究了在受主掺杂ＣａＴｉＯ３体系的ＯＣＭ反应中ＣＯ２的作用。受主杂质Ｌｉ＾＋，Ｍｇ＾２＋，Ａ＾３＋掺杂的ＣａＴｉＯ３的分压及吸附温度等因素有关。大部分吸附的ＣＯ２与催化剂中的Ｃａ（ＯＨ）２作用形成了ＣＯ３＾－，少部分与催化剂晶格中的活泼氧化物种     

掺杂钛酸盐对乙烷氧化脱氢催化性能的研究

在７００￣８５０℃范围内研究了掺杂ＣａＴｉＯ３、ＳｒＴｉＯ３催化剂用于乙烷氧化脱氢（ＯＤＨＥ）的催化行为，发现这类催化剂对ＯＤＨＥ均有一定的催化活性。适量的Ｌｉ＾＋取代Ｔｉ＾４＋后不仅提高了催化活性，而且改善了催化剂对乙烯的选择性。催化剂ＣａＴｉ０．９Ｌｉ０．１Ｏ３－δ在８５０℃时乙烷转化率和乙烯选择性分别为８７．８％和７１．７％。Ｓｒ对Ｃａ部分取代后制得的催化剂可在极宽的温度范围内（７００￣８５     

CATALYTIC BEHAVIOR OF DOPED MTiO_3 CATALYSTS FOR OXIDATIVE DEHYDROGENATION OF ETHANE

用Ｌｉ＋部分替代ＭＴｉＯ３（Ｍ＝Ｃａ、Ｓｒ）催化剂中的Ｔｉ４＋，明显地提高了乙烷氧化脱氢（ＯＤＨＥ）反应中乙烯的选择性。在ＣａＴｉ０．９Ｌｉ０．１Ｏ３－δ催化剂上，反应温度为８５０℃时，乙烯选择性为７７．４％，乙烷转化率为８１．７％。Ｌｉ掺杂的作用是增加了催化剂的Ｐ型半导性和未充分还原的氧物种数目。     

乙烷在钛酸盐复合氧化物上的氧化脱氢Ⅰ.锂掺杂对催化性能的影响

研究了掺杂钛酸盐催化剂用于乙烷氧化脱氢的催化行为，发现适量的Ｌｉ＾＋取代Ｔｉ＾４＋后可明显改善催化剂对乙烯的选择性。催化剂ＣａＴｉ０．９Ｌｉ０．１Ｏ３－δ在８５０℃时乙烷转化率和乙烯选择性分别为８７．８％和７１．７％，乙类的单程收经为６３．０％．催化剂Ｓｒ０．９Ｃａ０．１Ｔｉ０．９Ｌｉ０．１Ｏ３－δ可在极宽的温度范围内保持很高的乙烯选择性。     

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     

Bi—Mo—Nb复合氧化物催化作用机理的ESR和XPS研究

用ＥＳＲ对比研究了掺杂Ｎｂ对α－Ｂｉ２Ｍｏ３Ｏ１２催化剂丙烯还原和氧再氧化的影响，并用ＸＰＳ原位Ａｒ＾＋溅射研究了催化剂的还原与再氧化过程，观察了上述过程中催化剂内金属离子的价态变化和晶格氧的扩散现象，提出了Ｂｉ－Ｍｏ间通过晶格氧扩散所发生的氧化还原作用及模型，探讨了Ｎｂ＾５＋取代ＭＯ＾６＋产生的氧空位对加速晶格氧扩散所起的作用。     

铈离子清除超氧物自由在的机理

以光辐照核黄素作为超氧物自由基（Ｏ２）源，研究了Ｃｅ＾３＋、Ｃｅ＾４＋对硝基四氮唑蓝（ＮＢＴ）还原、羟胺化的抑制作用和铈离子存在时Ｈ２Ｏ２含量、核黄素光分解、溶解氧消耗和变化以及铈离子价态的变化。从而得知，铈离子可清除Ｏ２，其机理为：Ｃｅ＾３＋供给Ｏ２电子氧化为Ｃｅ＾４＋、Ｏ２还原为Ｈ２Ｏ２；Ｃｅ＾４＋从Ｏ２获得电子还原为Ｃｅ＾３＋，Ｏ２氧化为Ｏ２。所以微量的铈离子可清除大量的Ｏ２。     

卟啉化合物电化学性质研究 Ⅰ.5,10,15,20-四-(4-乙酰氧基苯)卟吩及其Cu、Zn、Fe、Co、Ni配合物的合成及循环伏安研究

本文报道了５，１０，１５，２０－四（４－乙酰氧基苯）卟吩（Ｔ（４ＡＯＰ）Ｐ）及其Ｃｕ，Ｚｎ，Ｆｅ，Ｃｏ，Ｎｉ配合物的合成及其在ＣＨ２Ｃｌ２－０．１ｍｏｌ／ＩＴＢＡＰ体系中的循环伏安（ＣＶ）。研究结果。ＣＶ实验表明：Ｃｕ＾２＾＋，Ｚｎ＾２＾＝，Ｎｉ＾２＾＋离子以稳定的＋２价存在于Ｔ（４ＡＯＰ）Ｐ中，电子转移反应在卟啉环上进行，而Ｆｅ＾３＾＋，Ｃｏ＾２＾＋离子在氧化还原过程中发生价态变化。实验发现...     

YBCO超导体中B位元素替代的簇模型的计算研究

电计算电荷分布讨论了元素的氧化态，指出ＹＢＣＯ中不存在Ｃｕ＾３＾＋，计算得到Ｂ位的Ｂａ，Ｓｒ等元素有负电荷，直接解释了Ｂａ３ｄ，Ｂａ４ｄ束缚能ＸＰＳ测定的“反常”结果。同时指出Ｂ位元素与其配位氧原子形成电子库，其容量由Ｂ位原子上负电荷大小标志，它与Ｏ２ｐ空穴相关，还讨论了Ｙ／ＢＣＯ中一些化学键的性质，它们可能与高温超电性相关联。     

三卤代锡钨（钼）双核化合物的制备和晶体结构

ＣｐＭ（ＣＯ）３ＳｎＰｈ３和ＣｐＭ（ｃｏ）３ｓＮｐＨ２ｘ（Ｃｐ＝Ｃ５Ｈ４ＣＨ３，Ｃ５Ｈ４ＣＯＣＨ３；Ｍ＝Ｍｏ，Ｗ；Ｘ＝Ｃｌ，Ｂｒ）与ＨＣｌ或ＨＢｒ发生取代反应，得到三氯、三溴以及混合三卤代锡钨（钼）双核化合物，并经元素分析、＾１Ｈ ＮＭＲ、ＩＲ表征。化合物Ｃｌ３ＳｎＷ（ＣＯ）３Ｃ５Ｈ４ＣＯＣＨ３的晶体属单斜晶系，空间群为Ｐ２１／ｃ，ａ＝０．７６８６（３）ｎｍ，ｂ＝１．２６２２（２）ｎｍ，ｃ＝１．６     

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.     

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.     

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.