氟氯有机化合物对HZSM-5分子筛改性过程中氟和氯的作用

利用ＸＲＤ，ＭＡＳ，ＮＭＲ，ＩＲ和ＸＰＳ等手段研究了ＣＦ４－ｎＣｌｎ改性的ＨＺＳＭ－５分子筛的体相和表面结构的变化。结果表明，改性过程中Ｆ和Ｃｌ均能使ＨＺＳＭ－５脱铝和脱硅。Ｃｌ可以使沸石骨架ＳｉＯ２／Ａｌ２Ｏ３升高，而Ｆ除使沸石骨架脱铝外，还会极化其晶格。Ｆ比Ｃｌ更容易在沸石表面富集。Ｆ和Ｃｌ是通过取代Ｏ或ＯＨ与沸石表面Ｓｉ或Ａｌ作用的。改性后的沸石表面有数种含氟表面物种存在。     

（四甲基二硅撑）双（3—三甲硅基环戊二烯基）—四羰基二铁…

标题化合物（Ｍｅ２ＳｉＳｉＭｅ２）〔η＾５－（３－Ｍｅ３ＳｉＣ５Ｈ３）Ｆｅ（ＣＯ）２〕２／（μ－ＣＯ）２（Ａ）分子中的Ｆｅ－Ｆｅ键被钠汞齐还原断裂，生成相应的双铁负离子，分别与ＭｅＣＯＣｌ、ＰｈＣＯＣｌ、ＰｈＣＨ２Ｃｌ、ＣｌＣＨ２ＣＯＯＣ２Ｈ５和Ｐｈ３ＳｎＣｌ进行亲核取代反应，生成在铁原子上引入相应取代基的产物（Ｍｅ２ＳｉＳｉＭｅ２）〔η＾５－（３－Ｍｅ３ＳｉＣ５Ｈ３）Ｆｅ（ＣＯ）２Ｒ〕２（Ｒ：Ｍ     

蒸汽相法硼硅MFI沸石的合成与表征

在三乙胺（Ｅｔ３Ｎ）－乙二胺（ＥＤＡ）－Ｈ２Ｏ蒸汽相中，无定形凝胶Ｎａ２Ｏ－Ｂ２Ｏ２－ＳｉＯ２－Ｈ２Ｏ晶化生成硼硅ＭＦＩ（ＺＳＭ—５）沸石．研究了硼硅ＭＦＩ沸石的适宜晶化条件，以及氯化钠、碳酸钠和磷酸钠取代氢氧化钠作为钠源的影响．晶体结构参数、１１ＢＮＭＲ、ＦＴ－ＩＲ的结果表明，由蒸汽相法合成的硼硅ＭＦＩ沸石，其硼原子进入了沸石骨架．     

TiO2,la2O3,ZrO2改性Pd／SiO2催化剂吸氢性能及反应活性的研究

ＴｉＯ２，Ｌａ２Ｏ３和ＺｒＯ２以单层形式分布在ＳｉＯ２上制得了Ｐｄ催化剂。经４７３Ｋ（ＬＴＲ）及７７３Ｋ（ＨＴＲ）Ｈ２处理后，进行Ｈ２－Ｏ２滴定反应，测定催化剂对Ｈ２的吸附能力。结果表明，Ｐｄ／ＴｉＯ２／ＳｉＯ２，Ｐｄ／Ｌａ２Ｏ３／ＳｉＯ２及Ｐｄ／ＺｒＯ２／ＳｉＯ２的吸氢能力高于单一载体Ｐｄ催化剂的吸能力，说明ＳｉＯ２骨架经涂层氧化物的改性，Ｐｄ得到较好的分散。Ｐｄ与载体之间相互作用为：Ｐｄ／Ｔｉ     

铁硅酸盐分子筛乙苯氧化脱氢催化性能研究：II.FeZSM—5的酸碱性质和…

本文应用碱性气体吸附的红外光谱和ＴＰＤ技术研究了ＦｅＺＳＭ－５（Ｆ４）的酸性，酸性为：Ｈ－Ｆ４〉Ｆｅ２Ｏ３／Ｆ４〉Ｆ４原粉〉水热处理的Ｋ－Ｆ４〉Ｌｉ－Ｆ４〉Ｎａ－Ｆ４〉Ｋ－Ｆ４〉ＮａＯＨ／Ｆ４。比较了酸强度和积炭对乙苯氧化脱氢性能的影响，以及催化剂酸碱性质与积炭的关系。结果表明，乙苯氧化脱氢反应是在酸碱协同作用下进行的，积炭也参与了氧化脱氢反应，催化剂表面上Ｌ酸中心产生的具有一定Ｃ、Ｈ、Ｏ比的积炭     

金属─助剂相互作用对SiO_2载铑催化剂化学吸附的影响Ⅰ．Rh_2－V／SiO_2催化剂

本文用化学吸附、原位ＩＲ、和ＸＰＳ考察了钒助剂对Ｒｈ２／ＳｉＯ２催化剂的Ｈ２和ＣＯ化学吸附的影响．结果表明，１）ＣＯ吸附在ＲｈＩ、ＲｈⅡ和ＲｈⅢ中心上分别产生孪生、线式和桥式ＣＯ表面吸附物种．２）Ｈ２主要解离吸附在ＲｈⅡ和ＲｈⅢ中心上，但ＣＯ能优先吸附；ＲｈＩ中心对Ｈ２的化学吸附能力弱，但Ｈ２和ＣＯ能共吸附在ＲｈＩ中心上形成表面羰基氢化物．３）Ｒｈ２－Ｖ／ＳｉＯ２催化剂在５７３Ｋ还原后，铑与钒助剂的强相互作用主要发生在ＲｈⅡ和ＲｈⅢ与钒助剂之间，Ｈ２吸附比ＣＯ吸附受到更强烈的抑制．用覆盖模型可以较好地解释钒助剂对Ｒｈ２／ＳｉＯ２催化剂的Ｈ２和ＣＯ化学吸附的影响．     

丙炔醇聚合股对铁在酸性溶液中的缓蚀作用

应用电化学交流阻抗谱技术研究了Ｆｅ／Ｈ_２ＳＯ_４与Ｆｅ／Ｈ_２ＳＯ_４＋Ｈ_２Ｓ体系中丙炔醇（ＰＡ）聚合膜的形成及其缓蚀作用,同时利用ＳＥＭ、ＡＦＭ及ＥＤＸ对ＰＡ聚合不同时期铁表面腐蚀形貌进行观测与成分分析．结果表明,Ｆｅ／Ｈ_２ＳＯ_４与 Ｆｅ／Ｈ_２ＳＯ_４＋ Ｈ_２Ｓ体系中 ＰＡ可逐渐聚合成膜,从而有效抑制基体的腐蚀,使电极表面较为平整,微米尺度下呈现规则的块状结构;但Ｆｅ／Ｈ_２ＳＯ_４体系中宏观上ＰＡ并未形成连续的保护膜,导致电极表面局部发生腐蚀;而Ｆｅ／Ｈ_２ＳＯ_４＋Ｈ_２Ｓ体系中,Ｈ_２Ｓ、ＨＳ－在电极表面的吸附减缓了ＰＡ聚合成膜,但长时间腐蚀后,由于硫化物的生成覆盖在ＰＡ聚合膜上,使其具有长期缓蚀效能．     

镍盐和氧化镍在NaY沸石中存在状态研究

用ＸＲＤ、ＥＸＡＦＳ和ＴＰＲ方法研究了Ｎｉ（ＮＯ３）２／ＮａＹ和ＮｉＯ／ＮａＹ分散体系。在沸石上，Ｎｉ（ＮＯ３）２的分散比ＮｉＯ容易得多。ＸＲＤ相定量方法测定的ＮｉＯ在ＮａＹ沸石上的分散阈值很低，仅为密置单层容量的２％左右。在分散阈值关ＮｉＯ在沸石上处于分散相和笼外小晶粒两种状态。分散相ＮｉＯ比笼外ＮｉＯ小晶粒难还原。样品中ＮｉＯ含量超过阈值时，笼外小晶粒长大成ＸＲＤ可检测的较大晶粒。     

CoMoK／γ—Al2O3水煤气变换催化剂的硫化及反硫化

以Ｈ２Ｓ和ＣＳ２作硫化剂，用ＰＰＳ和ＴＰＤＳ方法研究了水煤气变换催化剂ＣｏＭｏＫ／γ－Ａｌ２Ｏ３的硫化及反硫化过程。用Ｈ２Ｓ／Ｈ２硫化时，只发现Ｈ２Ｓ的消耗和Ｈ２Ｏ的生成，用ＣＳ２／Ｈ２硫化时，只发现Ｈ２Ｓ的消耗和Ｈ２Ｏ的生成。用ＣＳ２／Ｈ２硫化时，首先生成ＣＯ２，然后是ＣＨ４，Ｈ２Ｏ和Ｈ２Ｓ，ＴＰＧ实验表明催化剂表面上积炭，造成催化剂和活性降低，但积炭在水煤变换反应进行了逐渐除法。ＴＰＤＳ实验表     

CO2和CH3OH直接合成碳酸二甲酯Cu-Ni/V2O5-SiO2催化剂

采用表面反应改性法制备了Ｖ２Ｏ５－ＳｉＯ２（ＶＳｉＯ）表面复合物,用等体积浸渍法制备了ＶＳｉＯ担载的Ｃｕ－Ｎｉ双金属催化剂,用ＩＲ,ＴＰＤ,ＴＰＳＲ和微反技术研究了ＣＯ２和ＣＨ３ＯＨ在催化剂表面上的化学吸附与反应性能。结果表明,在Ｃｕ－Ｎｉ／ＶＳｉＯ催化剂上存在着金属位Ｃｕ－Ｎｉ合金,Ｌｅｗｉｓ酸位Ｖ＾ｎ＋和Ｌｅｗｉｓ碱位Ｖ＝Ｏ三类活性中心;ＣＯ２在金属位和Ｌｅｗｉｓ酸位协同作用下可生成ＣＯ２卧式     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

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.     

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%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

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.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

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.