单层分散型Pt/Ni双金属催化剂的制备及其C=C和C=O催化加氢性能

 利用金属置换反应制备了表面单层分散型Pt/Ni双金属催化剂,并测定了该催化剂对环己烯、苯乙烯、丙酮和丁醛气相加氢反应的催化性能. 结果发现,这种催化剂具有比传统浸渍法制备的相同Pt含量的Pt/Ni和Pt/Al2O3催化剂更高的催化活性.     

Pd/C和Raney Ni催化剂的制备及其催化活性比较

制备了Pd/C和Raney Ni催化剂,其结构和性能经XRD,BET和SEM表征。并以呋喃加氢制备四氢呋喃为探针反应,对两种催化剂的催化活性进行了比较,探讨了反应温度、反应压力和催化剂用量对转化率和选择性的影响,结果表明:Raney Ni的催化活性优于Pd/C。     

Ba修饰的Pd/A12O3对苯酚液相原位加氢制环己酮反应的催化性能

利用等体积浸渍法制备了一系列不同助剂修饰的Pd/AI2O3催化剂,并考察了催化剂对苯酚液相原位加氢制环己酮反应的催化性能.结果表明,Ba-Pd/AI2O3对苯酚液相原位加氧反应有较优的催化性能.当w(Ba)=3%时,苯酚转化率可比Pd/AI2O3催化剂提高近2倍.在优化的反应条件下,苯酚转化率可达100%,环己酮收率可达80%.利用透射电子显微镜、CO化学吸附、X射线衍射、N2吸附-脱附和CO2程序升温脱附等手段表征了不同Ba含量的Pd/AI2O3催化剂的物理化学性质.结果表明,Ba的添加可明显提高Pd在AI2O3表面的分散度,同时增强了催化剂表面的碱性.这是Ba-Pd/AI2O3对苯酚液相原位加氢制环己酮反应具有较优催化性能的重要原因.     

基于磁性金属有机骨架材料的多功能催化剂Fe_3O_4@IRMOF-3/Pd的制备及催化性能

采用逐层自组装方法制备了磁性Fe_3O_4@IRMOF-3复合材料,通过浸渍法将Pd纳米粒子负载到Fe3O4@IRMOF-3上,得到多功能催化剂Fe3O4@IRMOF-3/Pd.用粉末X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)及原子吸收(AAS)等方法对材料的组成和结构进行了表征,并考察了催化剂在Knoevenagel缩合反应、Suzuki偶联反应和烯烃催化加氢反应中的催化性能.结果表明,磁性Fe3O4@IRMOF-3/Pd催化剂在Knoevenagel缩合反应和Suzuki偶联反应中均表现出较好的催化活性和一定的循环稳定性.在烯烃的催化加氢反应中,催化剂可以高效催化多种烯烃的加氢反应,并表现出对底物的尺寸选择性.在苯乙烯的催化加氢反应中,催化剂循环使用9次,转化率依然大于99%,并且催化剂结构没有明显变化.     

IB金属对Ni/SiO2催化剂乙炔选择性加氢反应性能的影响

乙烯是合成聚乙烯的原料,其主要来源是石油裂解气,其中少量的乙炔杂质会严重毒化生产聚乙烯的催化剂,因此需要将其去除.对于乙炔选择加氢反应,传统工业上使用的是Pd基催化剂,尽管其乙炔转化率很高,但对乙烯的选择性很低.我们前期的研究发现,IB族金属(Au,Ag和Cu)与Pd形成的合金单原子催化剂可以有效地提高乙烯的选择性.作为与Pd同组的非贵金属,Ni催化剂在多种催化加氢反应中显示出优异活性,而在乙炔选择加氢反应中,Ni是否能够替代贵金属Pd尚无定论.本文系统地研究了IB金属对Ni/SiO2催化剂乙炔选择性加氢性能的影响.与Pd/SiO2催化剂不同,单金属Ni/SiO2催化剂在低温下不具有活性.将IB金属添加到Ni/SiO2催化剂中,可以显著提高其催化活性以及对乙烯的选择性.其中,AuNix/SiO2和CuNix/SiO2催化剂的催化活性随还原温度升高而提高,而AgNix/SiO2催化剂对预处理温度不敏感.通过调变IB/Ni原子比和还原温度优化了催化剂的催化性能,发现优化后的三种催化剂(CuNi0.125/SiO2、AgNi0.5/SiO2和AuNi0.5/SiO2)的活性和选择性随反应温度升高表现出相似的变化趋势.催化稳定性考察结果显示,CuNi0.125/SiO2催化剂表现出最高选择性和稳定性;尽管AuNi0.5/SiO2的初始活性最高,但是稳定性最低.采用XRD、TPR和微量吸附量热等表征手段对不同IB金属对Ni基催化剂性质的影响进行了系统考察.以Cu-Nix/SiO2催化剂为例,H2-TPR测试结果表明,Cu-Ni双金属纳米颗粒的形成使得还原温度低于相应的单金属催化剂,表明铜和镍之间存在明显的相互作用.此外,通过TPR获得的CuNix/SiO2催化剂上的氢气消耗量与理论耗氢量相吻合,表明在还原处理的过程中双金属催化剂中的CuO和NiO可以被完全还原.乙炔的微量吸附量热结果表明,在CuNi0.125/SiO2,AgNi0.5/SiO2,AuNi0.5/SiO2和Ni0.5/SiO2催化剂上的初始吸附热分别为187,196,304和103 kJ/mol,即它们的初始乙炔吸附强度顺序为AuNi0.5/SiO2>AgNi0.5/SiO2>CuNi0.125/SiO2>Ni0.5/SiO2.该结果与三者的初始催化活性顺序一致,表明IB金属的加入可以增强乙炔在催化剂表面的吸附,从而提高催化活性.     

活性炭负载钯催化剂对邻硝基甲苯波相加氢制邻甲苯胺的研究

本文研究了不同载体负载的钯催化剂对邻硝基甲苯催化加氢制邻甲苯胺的性能,考察了载体的性能、钯的分散度对催化加氢速率的影响,探讨了该反应的动力学特征.结果表明,Pd/C催化剂液相催化邻硝基甲苯加氢制邻甲苯胺活性高,选择性好,寿命长.该反应为双分子吸附的表面反应.属于非择形反应.     

腐植酸负载金属配合物对Heck反应的催化性能

以腐植酸为原料,通过简单的方法制得了腐植酸负载Pd(HA-Pd)和腐植酸负载Pd/Ni催化剂(HA-Pd/Ni).用NaBH4作为还原剂,得到腐植酸负载Pd和腐植酸负载Pd/Ni催化剂的还原产物(HA-Pd(0)和HA-Pd/Ni(0)).研究了腐植酸负载Pd和腐植酸负载Pd/Ni催化剂及其还原产物对芳基卤与乙烯基化合物的Heck反应的催化性能.结果显示,该类催化剂均能够很好地催化溴苯与丙烯酸的Heck芳基化反应.     

IB金属对Ni/SiO_2催化剂乙炔选择性加氢反应性能的影响（英文）

乙烯是合成聚乙烯的原料,其主要来源是石油裂解气,其中少量的乙炔杂质会严重毒化生产聚乙烯的催化剂,因此需要将其去除.对于乙炔选择加氢反应,传统工业上使用的是Pd基催化剂,尽管其乙炔转化率很高,但对乙烯的选择性很低.我们前期的研究发现,IB族金属(Au,Ag和Cu)与Pd形成的合金单原子催化剂可以有效地提高乙烯的选择性.作为与Pd同组的非贵金属,Ni催化剂在多种催化加氢反应中显示出优异活性,而在乙炔选择加氢反应中,Ni是否能够替代贵金属Pd尚无定论.本文系统地研究了IB金属对Ni/SiO_2催化剂乙炔选择性加氢性能的影响.与Pd/SiO_2催化剂不同,单金属Ni/SiO_2催化剂在低温下不具有活性.将IB金属添加到Ni/SiO_2催化剂中,可以显著提高其催化活性以及对乙烯的选择性.其中,Au Ni_x/SiO_2和CuNi_x/SiO_2催化剂的催化活性随还原温度升高而提高,而AgNi_x/SiO_2催化剂对预处理温度不敏感.通过调变IB/Ni原子比和还原温度优化了催化剂的催化性能,发现优化后的三种催化剂(Cu Ni_(0.125)/SiO_2、AgNi_(0.5)/SiO_2和AuNi_(0.5)/SiO_2)的活性和选择性随反应温度升高表现出相似的变化趋势.催化稳定性考察结果显示,CuNi_(0.125)/SiO_2催化剂表现出最高选择性和稳定性;尽管Au Ni_(0.5)/SiO_2的初始活性最高,但是稳定性最低.采用XRD、TPR和微量吸附量热等表征手段对不同IB金属对Ni基催化剂性质的影响进行了系统考察.以Cu-Ni_x/SiO_2催化剂为例,H_2-TPR测试结果表明,Cu-Ni双金属纳米颗粒的形成使得还原温度低于相应的单金属催化剂,表明铜和镍之间存在明显的相互作用.此外,通过TPR获得的CuNi_x/SiO_2催化剂上的氢气消耗量与理论耗氢量相吻合,表明在还原处理的过程中双金属催化剂中的CuO和NiO可以被完全还原.乙炔的微量吸附量热结果表明,在CuNi_(0.125)/SiO_2,AgNi_(0.5)/SiO_2,Au Ni_(0.5)/SiO_2和Ni_(0.5)/SiO_2催化剂上的初始吸附热分别为187,196,304和103 kJ/mol,即它们的初始乙炔吸附强度顺序为Au Ni_(0.5)/SiO_2AgNi_(0.5)/SiO_2CuNi_(0.125)/SiO_2Ni_(0.5)/SiO_2.该结果与三者的初始催化活性顺序一致,表明IB金属的加入可以增强乙炔在催化剂表面的吸附,从而提高催化活性.     

介孔碳负载的Pd催化剂催化β-谷甾醇加氢制备β-谷甾烷醇

采用液相还原法制备了介孔碳(CMC)担载的Pd催化剂,用于β-谷甾醇加氢制备β-谷甾烷醇反应.与活性碳担载的Pd催化剂相比,Pd/CMC的活性更高,这归因于该催化剂具有较大的孔径,从而有利于较大分子的催化加氢反应.     

高(111)晶面暴露的Pd纳米颗粒的制备与表征及其加氢性能

通过液相氢气还原法,在不同温度下制备出了不同（111）晶面占比的Pd单晶纳米颗粒,用活性炭吸附制备成Pd/C纳米催化剂。通过透射电子显微镜（TEM）、傅里叶变换（FFT）、X射线衍射（XRD）表征证实了低温下制备的Pd纳米颗粒具有较高的（111）晶面占比。氢氧脉冲滴定（H₂-O₂）和H₂-程序升温脱附（H₂-TPD）结果显示,上述催化剂表面吸附氢气量与其Pd（111）晶面占比呈线性关系。此外,该系列Pd/C催化剂具有相似的粒径4.3 nm以及较窄的尺寸分布,相近的孔隙参数和Pd负载量,从而可对比（111）晶面比例差异对其加氢性能的影响。3个探针反应（苯乙烯、环己烯和对硝基甲苯的加氢反应）的实验结果表明,相比于低（111）晶面暴露比例的Pd/C催化剂,含有高（111）晶面暴露比例的Pd/C催化剂显示出更高的加氢活性,且Pd（111）晶面比例与氢气消耗速率呈一定的线性关系,这归因于H₂优先吸附于Pd（111）晶面促进了活性氢原子的形成。基于以上分析,高（111）晶面暴露的Pd基催化剂有利于加氢性能的提高。     

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.     

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.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.