制备高碳醇用Cu-Fe系催化剂的活性相

用共沉淀法制备了Ｃｕ－Ｆｅｘ系催化剂，它是由脂肪酸甲酯加氢制备高碳醇的新催化体系。催化剂经焙烧后的物相为ＣｕＯ，γＦｅ２Ｏ３和ＭｇＯ，形成了活性相的结构前驱。     

F-T合成非负载型Fe-Mn催化剂的晶相结构与反应性能

Ｆｅ－Ｍｎ催化剂前驱体在焙烧时生成α（Ｆｅ１－ｙＭｎｙ）２Ｏ３、γ－（Ｍｎ,Ｆｅ）３Ｏ４和β-（Ｍｎ,Ｆｅ）２Ｏ３。焙烧过的前驱体在氢气氛中还原时生成（Ｆｅ１－ｘ、Ｍｎｘ）３Ｏ４、（Ｍｎ,Ｆｅ）３Ｏ４、Ｆｅ１－ｚＭｎｚＯ、（Ｍｎ,Ｆｅ）Ｏ和Ｆｅ０。当还原处理过的前驱体被置于合成气中时,随着反应环境的变化Ｆｅ０转变为碳化铁、Ｆｅ１－ｚＭｎ２Ｏ,最终成为（Ｆｅ１－ｘＭｎｘ）３Ｏ４。锰在催化剂中起着电子及结构双重作用。在催化过程中,所有的晶相均表现出一氧化碳加氢活性。然而,它们的催化性能与反应环境密切相关。     

氧化铈在非贵金属氧化物催化剂中的作用：Ⅵ.Cu—Fe—Ce—O催化剂的结 …

采用ＸＲＤ,顺磁共振（ＥＳＲ）,Ｍｏｓｓｂａｕｅｒ和或温还原（ＴＰＲ）技术对负截型Ｃｕ－Ｆｅ－Ｏ（Ⅰ）,Ｃｕ－Ｆｅ－Ｃｏ－Ｏ（Ⅱ）催化剂的固相结构及热稳定性进行了研究。结果发现,（Ⅰ）中主要存在Ｆｅ２ＣｕＯ４,ＣｕＯ和颗粒度小于１３ｎｍ的Ｆｅ２Ｏ３相。随着焙烧温度的升高,ＣｕＯ晶相逐渐消失,Ｆｅ２ＣｕＯ４的晶相长大。（Ⅱ）中Ｃｅ的存在,能提高Ｃｕ＾２＋的浓度,抑制ＣｕＯ和Ｆｅ２ＣｕＯ４晶相的生成,     

Fe_2O_3／ZrO_2催化剂上一氧化碳加氢反应制低碳烯烃 Ⅱ．预处理条件对催化剂结构及性能的影响

用ＴＰＲ，Ｍｏｓｓｂａｕｅｒ谱法，ＸＰＳ，ＸＲＤ及反应评价等手段研究了Ｆｅ２Ｏ３／ＺｒＯ２催化剂的还原行为、铁物种状态和ＣＯ加氢反应性能．结果表明，预处理条件明显影响Ｆｅ２Ｏ３／ＺｒＯ２催化剂表面铁原子的数量、铁锆间的相互作用、催化剂的物相变化以及ＣＯ加氢反应的催化性能．以Ｆｅ２Ｏ３／ＺｒＯ２经氢氟混合气程序升温至７５３Ｋ还原生成的Ｆｅ－Ｚｒ－Ｏ物种为前身，在合成气中进一步还原得到的铁锆催化剂，具有较好的Ｆ－Ｔ反应合成低碳烯烃的选择性．     

Mn－Ag／γ－Al_2O_3催化剂中氧的性能

本文运用ＴＰＲ、ＴＰＤ－ＭＳ、ＸＲＤ等技术研究了Ｍｎ－Ａｇ／γ－Ａｌ_２Ｏ_３催化剂的还原性能和再氧化能力．结果表明，Ｍｎ－Ａｇ／γ－Ａｌ_２Ｏ_３中银物相由Ａｇ￣０和Ａｇ_２Ｏ组成，锰物相由β－ＭｎＯ_２和Ｍｎ２Ｏ_３组成．Ｍｎ／γ－Ａｌ_２Ｏ_３催化剂的ＴＰＲ有二个还原峰，分别是ＭｎＯ_２和Ｍｎ_２Ｏ_３的还原．Ａｇ促使ＭｎＯ_２和Ｍｎ_２Ｏ_３的还原明显向低温方向移动，而且ＭｎＯ_２和Ｍｎ_２Ｏ_３的还原峰融合成一个还原峰．Ｍｎ－Ａｇ／γ－Ａｌ_２Ｏ_３的ＴＰＤ有三个脱氧峰，随着Ａｇ含量增加，峰Ⅰ向高温方向移动，Ｍｎ￣（４＋）２ｐ３／２的电子结合能增加，并且催化剂的再氧化能力增强．催化剂ＣＯ的氧化活性与催化剂的再氧化能力有很好的对应关系．     

氧化铈在非贵金属氧化物催化剂中的作用 Ⅵ.CuFeCeO催化剂的结构与热稳定性

采用ＸＲＤ, 顺磁共振（ＥＳＲ） , Ｍｏｓｓｂａｕｅｒ 和程序升温还原（ＴＰＲ） 技术对负载型ＣｕＦｅＯ（ Ⅰ） ,ＣｕＦｅＣｅＯ（ Ⅱ） 催化剂的固相结构及热稳定性进行了研究。结果发现,（ Ⅰ） 中主要存在Ｆｅ２ＣｕＯ４ ,ＣｕＯ 和颗粒度小于１３ ｎｍ 的Ｆｅ２Ｏ３ 相。随着焙烧温度的升高,ＣｕＯ 晶相逐渐消失,Ｆｅ２ＣｕＯ４ 的晶相长大。（ Ⅱ） 中Ｃｅ的存在, 能提高Ｃｕ２＋ 的浓度, 抑制ＣｕＯ 和Ｆｅ２ＣｕＯ４ 晶相的生成, 能消除催化剂中ＣｕＯ 与ＦｅＯ中氧在还原时的差异, 但抑阻Ｆｅ２Ｏ３ 晶相生成的效果不明显。在８００ ℃的高温环境中,Ｃｅ 的存在能有效地防止Ｆｅ２Ｏ３ 颗粒的长大, 提高催化剂中活性相的热稳定性以防止烧结, 同时使催化剂的低温还原性能有所提高。     

CuO／CeO2和CuO／Al2O3催化剂的催化性能

本文以ＣＯ氧化为模式反应考察了ＣｅＯ２和Ａｌ２Ｏ３负载氧化铜催化剂的氧化活性，运用ＸＲＤ和ＴＰＲ技术研究了催化剂的还原性能和物相结构，结果表明：载体性质对负载ＣｕＯ催化剂的ＣＯ氧化活性有很大影响，ＣｕＯ／ＣｅＯ２催化剂活性明显高于ＣｕＯ／Ａｌ２Ｏ３催化剂．催化剂的还原特性随载体不同而不同．同时发现，热处理对催化剂铜物种的存在形式，晶粒大小、还原特性及其催化活性有明显影响，ＣｕＯ／Ａｌ２Ｏ３催化剂活性下降的主要因素是生成了活性较低的ＣｕＡｌ２Ｏ４相，而ＣｕＯ／ＣｅＯ２催化剂活性下降是由于ＣｕＯ和ＣｅＯ２发生烧结，晶粒变大     

助剂对超细CuO－ZnO－SiO_2催化剂性质和CO_2加氢反应性能的影响

研究了９种助剂对用于ＣＯ２加氢反应的超细ＣｕＯ－ＺｎＯ－ＳｉＯ２催化剂性能的影响，并进行了ＸＲＤ和ＴＰＲ表征．结果表明，助剂影响超细催化剂的性质和催化性能，ＴｉＯ２、ＣｅＯ２、ＭｇＯ和Ｌａ２Ｏ３是ＣＯ２加氢合成甲醇的超细ＣｕＯ－ＺｎＯ－ＳｉＯ２催化剂体系的优良助剂．在含有不同助剂的ＣｕＯ－ＺｎＯ－ＳｉＯ２催化剂体系内存在ＣｕＯ和ＺｎＯ晶相，但除ＣｅＯ２以外，其它的助剂都可能以微晶或无定型的形式存在．ＴＰＲ研究表明，添加的助剂除ＣｅＯ２以外，都使超细ＣｕＯ－ＺｎＯ－ＳｉＯ２催化剂的还原温度提高，而且助剂对ＣｕＯ－ＺｎＯ－ＳｉＯ２催化剂活性的影响，按照助剂对ＣｕＯ－ＺｎＯ－ＳｉＯ２催化剂还原温度的影响进行了探讨     

镧改性铁催化剂的TPR技术和MES法研究

对负载Ｆｅ２Ｏ３－Ｌａ２Ｏ３－γ－Ａｌ２Ｏ３催化剂的ＴＰＲ，ＭＥＳ方法的研究表明，氧化镧对γ－Ａｌ２Ｏ３的改性，增强了活性组分同载体的相互作用，并使Ｆｅ２Ｏ３－Ｌａ２Ｏ３－γ－Ａｌ２Ｏ３催化剂在还原过程中稳定了亚铁离子相，在Ｆｉｓｃｈｅｒ－Ｔｒｏｐｓｃｈ合成反应未检测到碳化物相的生成。     

氧化铈对氧化锰结构和催化性能的影响

以共沉淀法制备了铈－锰混合氧化物催化剂，采用Ｘ射线衍射分析、程序升温脱附－质谱检测、程度升温还原等手段考察了催化剂的结构还原活性及表面氧脱附性能。结果表明，单组分ＭＮ－Ｏ催化剂的晶相结构为方铁锰矿型Ｍｎ２Ｏ３，双组分Ｍｎ－Ｃｅ－Ｏ催化剂为γＭｎ２Ｏ３和ＣｅＯ２。氧化铈的存在不影响氧化锰ＴＰＤ－Ｏ２特征峰的位置，但表面吸附氧量明显增加，并同催化剂对甲醇的完全氧化活性进行了关联，当Ｍｎ／Ｃｅ原子比为４     

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%).     

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.     

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.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

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.