离子液体制备纳米钯催化碘代芳烃双羰化反应合成α-酮酰胺

离子液体作为一种绿色溶剂,因其具有独特的性质和功能可以稳定产生的纳米钯颗粒.用离子液体制备了纳米钯催化剂,并成功地应用于碘代芳烃的双羰化反应,从而合成了一系列的α-酮酰胺,最高收率可达83%,丰富了α-酮酰胺的合成方法.该催化体系应用于碘代芳烃双羰化反应具有广泛的底物适应性.     

功能离子液体复合体系中钯催化的Heck偶联反应

在[BMIM][TPPMS]离子型膦配体和碱性离子液体 [BMIM][OAc] 组成的功能离子液体复合体系中, PdCl2(CH3CN)2可以有效地催化溴苯和丙烯酸乙酯的交叉偶联(Heck)反应, 产物肉桂酸乙酯(反式)的收率达到60%. 锚定在功能离子液体复合体系中的Pd催化剂循环使用11次后仍保持良好的活性和稳定性. 该催化剂体系的良好活性和稳定性可归因于三个方面: [BMIM][TPPMS]和[BMIM][OAc]间的协同配位效应; 以[BMIM][OAc]作为Heck反应的缚酸剂, 避免了无机盐粘稠物的形成; 生成的副产物[BMIM]Br可以有效溶解钯黑, 避免了钯黑的析出. 该离子液体催化体系对不同底物的Heck偶联反应也表现出良好的普适性.     

高效可循环离子型钯配合物催化羰化Sonogashira反应

炔酮类化合物作为一类具有生物活性的分子,是天然产物全合成中构建杂环类化合物的重要中间体.炔酮类化合物的传统合成方法是通过过渡金属催化金属有机炔烃和酰氯的交叉偶联,但存在酰氯本身稳定性和底物官能团耐受力较差的缺点.近年来,钯催化的羰化Sonogashira反应(末端炔烃和芳基卤化物与CO的偶联反应)成为合成炔酮类化合物更为直接和有效的方法,其中与钯中心原子配位的配体的电子效应和空间效应可显著调控钯配合物的催化性能.但均相钯催化的羰化Sonogashira反应体系存在催化剂流失、分离困难和难以循环使用的问题.我们以2-(1-咪唑基)噻唑为母体分子,合成了具有P,S,N杂合配体特征的配体L1,同时将配体L1通过与MeOTf的季铵化反应得到相应的离子型膦配体L2.在此基础上,利用L1和L2与过渡金属中心的配位作用合成相应的钯配合物1A和2A.由于L1和L2中含有多种不同配位能力的配体(P-配体,S-配体和/或N-配体),故通过N/S杂原子对Pd-中心原子的协同弱配位作用,可以调变相应钯配合物对羰化Sonogashira反应的催化性能.另外,2A中具有强吸电子效应的正电荷的存在,使其结构和催化性能也必然不同于中性配合物1A.实验结果表明,在温和的反应条件(90℃,lh,CO压强1.0 MPa)下,对于碘苯和苯乙炔的羰化Sonogashira偶联反应,1A体现出优于2A的催化性能,TOF值达到840 h-1;但反应温度提高到120℃时,1A的TOF高达3560 h-1,2A的TOF为2960 h-1.与L1的2JP-Se=744 Hz相比,L2的2JP-Se=768 Hz,说明L2中具有吸电子效应的正电荷的存在降低了相应P原子的σ给电子能力(2JP-Se数值越大,相应膦配体的6给电子能力越弱);同时,1A中具有弱配位能力的N配体的缺失削弱了配体对Pd活性中心的稳定作用.在底物普适性研究中发现,4-硝基溴苯在相同反应条件下几乎得不到羰化Sonogashira偶联产物.而将反应体系中的CO换为同样压强下的N2,却可以顺利实现Sonogashira偶联反应.我们推测,在CO氛围下形成的pd0-CO活性物种(与N2氛围下形成的Pd0活性物种相比)具有相对较低的对底物的氧化加成能力.离子型钯配合物2A的优势在于,当将其与室温离子液体[Bmim]PF6(溶剂)结合使用,在2A催化碘苯与苯乙炔的羰化Sonogashira偶联反应过程中,循环使用8次催化性能没有明显下降.     

NaY 分子筛超笼内离子液体和金属配合物自组装制备溶剂分子和金属配合物一体化催化剂

 采用自组装-瓶中造船法在 NaY 分子筛超笼内, 将溴化 1-癸基-3-甲基咪唑离子液体和邻菲罗啉钯组合成一体化催化剂, 并用于苯胺羰化反应. 结果表明, 相对于以离子液体为溶剂, 邻菲罗啉钯配合物/NaY 分子筛为催化剂的体系, 该一体化催化剂在离子液体和邻菲罗啉钯配合物用量显著降低的条件下, TOF 可达 23 000 h?1, 而相应均相催化剂体系的 TOF 仅为 3 060 h-1.     

钯/碳高效绿色催化Suzuki交叉偶联反应

开发了一个以钯/碳为催化剂高效绿色催化Suzuki反应制备联苯类化合物的新方法.该体系以环境友好的聚乙二醇400的水溶液为反应溶剂,加入离子液体1-甲基-3-丁基咪唑双三氟甲磺酰亚胺盐,可高效催化溴代芳烃与芳基硼酸的Suzuki交叉偶联反应,并且催化剂可以循环利用4次而催化效率没有明显降低.     

苯佐卡因合成实验的改进

基于绿色化学理念, 对传统基础有机化学实验苯佐卡因的制备进行了改进。以无溶剂法合成了离子液体乙基吡啶硫酸氢盐, 用其代替浓硫酸作为酯化反应催化剂, 同时考察了酸醇比、离子液体用量、反应时间及催化剂重复利用效率对反应的影响;使用钯碳-甲酸铵代替铁酸还原体系制备苯佐卡因, 考察了钯碳用量对反应的影响, 并简化了后处理过程。     

绿色离子液体中纳米钯催化剂的制备及其催化Heck-Mizoroki反应性能

发展了在非卤素绿色离子液体1-丁基-3-甲基咪唑离子液体乳酸盐中制备纳米Pd催化剂的简便化学方法.透射电镜结果表明,Pd纳米粒子高度分散在[Bmim]Lac离子液体中,平均粒径为2.2–3.1 nm.Pd纳米粒子的大小随着体系中[Bmim]Lac与Pd(OAc)2摩尔比减小和温度升高而增大.考察了离子液体稳定纳米Pd催化剂(PdNPs@[Bmim]Lac)催化Heck-Mizoroki反应性能,并对反应条件进行了优化.结果表明,所制备的离子液体稳定的纳米Pd催化剂在优化条件下可高效催化系列卤代芳烃与烯烃的Heck-Mizoroki反应,且可循环使用6次.     

离子液体中钯配合物催化苯胺氧化羰化制苯氨基甲酸甲酯

使用含氮钯配合物为催化剂,离子液体为反应介质,高效地实现了苯胺羰化制 苯氨基酸甲酯。其中使用Pd-(phen)_2(PF_6)_2为催化剂,MeBuImBF_4为溶剂时其 转化频率高于8000 mol·mol~(-1)·h~(-1),较使用离子液体以前提高了57倍。     

离子液体中无膦、无铜、钯催化的Sonogashira交联反应的研究

研究了离子液体中无膦、无铜、钯催化剂在Sonogashira交联反应中的催化性能. 系统考察了反应温度、溶剂、钯源、碱等因素的影响及底物的适用性. 研究结果表明, 该催化体系对各种电子效应的碘代烷和末端炔烃的Sonogashira交联反应是十分有效的, 反应在温和的条件下取得较好的收率. 此外, 该催化体系有很好的重复使用性, 循环四次后催化活性只有略微的降低.     

硅胶担载离子液体催化剂的制备及其在由胺制二取代脲反应中的应用

 采用溶胶-凝胶法制备了硅胶负载Rh(PPh3)3Cl-离子液体催化剂Rh-DMImBF4/SiO2-gel,并对其催化胺类化合物氧化羰化制二取代脲反应的活性进行了考察. 结果表明,该催化体系对胺类化合物氧化羰化制二取代脲反应具有较高的催化活性,产物分离简单,催化剂易回收且具有较好的重复使用性能. 以氧为氧化剂时,苯胺转化率可达95%,脲的选择性可达98%以上. 以硝基苯为氧化剂时,苯胺转化率为93%,硝基苯转化率为92%,脲的选择性为98%以上,转化频率均超过11000 mol/(mol·h). 此外,还制备了Co-DMImBF4/SiO2-gel,Pd-DMImBF4/SiO2-gel和Ru-DMImBF4/SiO2-gel等催化剂,并对其催化氧化羰化胺类化合物的性能进行了考察.     

钯-离子液体/钛硅复合氧化物催化剂的合及在胺羰化中的应用

长期以来 ,工业上一直使用光气合成法生产异氰酸酯类化合物 ,极易造成环境污染和人员伤害 ,因此研究无光气且环境友好的新工艺已引起广泛关注 .就经济角度考虑 ,由硝基类化合物进行还原羰化[1～ 4 ] 或胺类化合物进行氧化羰化 [5～ 13] 制备异氰酸酯比较有利 ,但是存在金属配合物催化剂的还原失活等问题[14 ,15] .室温离子液体作为一种具有特殊催化性能和可调控溶解能力的新型溶剂和反应介质已用于有机反应中 [16 ] ,但将其作为反应介质的含氮化合物进行羰化研究尚未见报道 .本文将离子液体应用于以硅酸四乙酯 ( TEOS)和钛酸四丁酯 ( TBO…     

无配体Pd/LDH-F催化剂在Heck和Suzuki反应中的应用

 以氟离子插层的水滑石LDH-F为载体,用逐滴浸渍法制备了新型Pd/LDH-F催化剂,并用其催化溴代芳烃的Heck和Suzuki偶联反应. 用X射线衍射表征了催化剂的晶相,以等离子体发射光谱测定了溶剂中钯的流失量. 结果表明,对于Heck反应,在无配体存在和低钯用量(Pd/溴代芳烃摩尔比为0.001)的情况下, Pd/LDH-F的催化性能优于其它载体负载的Pd催化剂,显示出很高的催化活性和选择性. 在140 ℃和12 h的条件下, Pd/LDH-F催化溴苯与苯乙烯Heck反应产物的收率可达86％, 反应后催化剂经过分离,可循环使用四次其催化活性基本不变. 在DMF/水摩尔比为0.5的混合溶剂中,在室温和3 h 的条件下, Pd/LDH-F (Pd/溴代芳烃摩尔比为0.005)催化溴苯与苯基硼酸盐的Suzuki反应中,目标产物收率为99%.     

Stabilized well-dispersed Pd(0) nanoparticles for aminocarbonylation of aryl halides

Well-dispersed palladium (0) nanoparticles stabilized with phosphonium based ionic liquid were synthesized conveniently and fully characterized. A catalyst system comprising of the Pd(0) nanoparticles and a base was found to be recyclable and efficient for the aminocarbonylation reaction of aryl iodide in ionic liquid media. In the presence of potassium tert-butyloxide, for the relatively stable aryl chloride and bromide substrates, medium activities were achieved for the catalyst. The catalyst composites can be recycled at least five times with sustained activity.     

Cross-linked polymer supported palladium catalyzed carbonylative Sonogashira coupling reaction in water

A cross-linked polymer-supported ionic liquid immobilized palladium catalyst, which is prepared by reaction of the Pd(OAc)₂ with copolymer of 3-butyl-1-vinylimidazolium iodide and divinylbenzene, was well characterized and employed as an effective heterogeneous catalyst for carbonylative Sonogashira coupling reaction of aryl iodides with terminal alkynes in water, affording the corresponding α,β-alkynyl ketones in good to excellent yields. The catalytic system not only solves the basic problem of homogeneous palladium catalyst recovery and reuse but also avoids the use of toxic phosphine ligands. The stability of supported palladium was also discussed.     

The role of Pd nanoparticles in ionic liquid in the Heck reaction

Pd(0) nanoparticles with approximately 2 nm diameter, immobilized in 1-n-butyl-3-methylimidazolium hexafluorophosphate ionic liquid, are efficient catalyst precursors for coupling of aryl halides with n-butylacrylate. In situ TEM analysis of the ionic liquid catalytic solution after the catalytic reaction shows the formation of larger nanoparticles ( approximately 6 nm). The palladium content in the organic phase during the arylation reaction was checked by ICP-AS and shows significant metal leaching (up 34%) from the ionic phase to the organic phase at low substrate conversions and drops to 5-8% leaching at higher conversions. These results strongly suggest that the Pd(0) nanoparticles serve as a reservoir of "homogeneous" catalytic active species.     

Ordered Mesoporous Organosilica with Ionic‐Liquid Framework: An Efficient and Reusable Support for the Palladium‐Catalyzed Suzuki–Miyaura Coupling Reaction in Water

The preparation of a novel palladium‐supported periodic mesoporous organosilica based on alkylimidazolium ionic liquid (Pd@PMO‐IL) in which imidazoilium ionic liquid is uniformly distributed in the silica mesoporous framework is described. Both Pd@PMO‐IL and the parent PMO‐IL were characterized by N₂‐adsorption–desorption, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), TEM, and solid‐state NMR spectroscopy. We have demonstrated that Pd@PMO‐IL is an efficient and reusable catalyst for the Suzuki–Miyaura coupling reaction of various types of iodo‐, bromo‐, and even deactivated aryl chlorides in water. It was also found that although the PMO‐IL nanostructure acts as reservoir for soluble Pd species, it can also operate as a nanoscaffold to recapture the Pd nanoparticles into the mesochannels thus preventing extensive agglomeration of Pd. This observation might be attributed to the isolated ionic liquid units that effectively control the reaction mechanism by preventing Pd agglomeration and releasing and recapturing Pd nanoparticles during the reaction process. The catalyst can be recovered and reused for at least four reaction cycles without significant loss of activity.     

A Non‐Phosgene Route Synthesis of Carbamate in Continuous Fixed Bed Reactor

A non‐phosgene route synthesis of carbamate was carried out in a continuous fixed‐bed reactor through oxidative carbonylation of aniline using palladium catalysts and sodium iodide as promoter. The activity, selectivity and stability of both carbon and alumina‐supported palladium catalysts were evaluated. It was found that the alumina‐supported catalyst system exhibited a higher activity and selectivity than that of the carbon‐supported system, and an average aniline conversion of 95.6% and carbamate selectivity of 74.6% were achieved for the Se‐Pd/Al₂O₃ catalyst after 91 h on stream. Reclamation analysis of the spent Pd/C catalyst suggested that the deactivation was mainly due to the leaching and sintering of palladium metal and the accumulation of insoluble chemicals on catalyst support also aggravated the decline of catalyst activity. When small amounts of selenium were added to the Pd/Al₂O₃ catalyst, its activity, selectivity and stability were significantly improved which indicated that a promotional effect existed for carbamate formation on a Pd‐Se catalyst system.     

New bis(N‐heterocyclic carbene) palladium complex immobilized on magnetic nanoparticles: as a magnetic reusable catalyst in Suzuki‐Miyaura cross coupling reaction

A new bis(N ‐heterocyclic carbene) (NHC) palladium complex supported on silica coated magnetic nanoparticles (MNPs) was prepared using the reaction of synthesized Pd‐NHC complex with MNPs. The Pd‐NHC complex was prepared using the reaction of a hydroxyl‐functionalized bis‐imidazolium ionic liquid. The Pd‐NHC organometallic complex was used as a heterogeneous recyclable and active catalyst in the Suzuki‐Miyaura reaction and various aryl halides were coupled with arylboronic acids in order to synthesize diverse biaryls in good to excellent yields. The prepared catalyst was characterized by use of some different microscopic and spectroscopic techniques including elemental analysis, FT‐IR spectroscopy, diffuse reflectance UV–Vis spectrophotometery, scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and X‐ray diffraction (XRD). The Pd‐NHC catalyst system is a magnetic reusable catalyst and it can be separated from the reaction mixture using an external magnetic field. The catalyst was reusable in the Suzuki‐Miyaura coupling reaction at least for 6 times without significant decreasing in its catalytic activity.     

Identification of surface states on finely divided supported palladium catalysts by means of inelastic incoherent neutron scattering

The purpose of the present investigation was to utilize the inelastic incoherent neutron scattering (INS) technique to reveal changes at the surface of technical catalysts under the influence of hydrogen in gas/solid interactions and during chemical reactions in a liquid-phase process. The formation and the properties of supported palladium hydride and changes of the hydrogen-related surface chemistry of the corresponding activated carbon supports in 20% Pd/C catalysts after short-term and long-term hydrogen cycling at different hydrogen pressures and temperatures were studied. The spectra indicate that hydrogenation of the activated carbon support by hydrogen spillover occurs to, partly, give a material that strongly resembles a-C:H (amorphous hydrogenated carbon). Indications for different relaxation phenomena and long-range phase coherence inside of supported particles of palladium hydride compared to hydrogenated palladium black were obtained. A 5% Pd/C catalyst after use in C-C coupling reactions, the Heck reaction of bromobenzene and styrene to stilbenes, was also studied after subsequent solvent extraction. Evidence for a preferential adsorption and accumulation of cis-stilbene at the catalyst surface was obtained. INS allows identification of a certain isomer from a complex reaction mixture preferentially adsorbed at the surface of a finely divided industrial heterogeneous catalyst.     

Carbonylative Suzuki coupling and alkoxycarbonylation of aryl halides using palladium supported on phosphorus‐doped porous organic polymer as an active and robust catalyst

Developing highly active catalysts with the combined advantages of molecular and solid catalysis is considered as the “Holy Grail” in the area of catalysis research. Herein, a phosphorus‐doped porous polymer‐immobilized palladium was successfully developed as an efficient, robust, and recyclable catalyst for the carbonylative Suzuki coupling and alkoxycarbonylation reactions of aryl halides. Rather than just as an immobilizing molecular catalyst, palladium supported on phosphorus‐doped porous organic polymer exhibits even better catalytic performances than that of its analogue homogeneous catalysts in both carbonylation reactions. Moreover, the catalyst can be easily separated and reused for at least 5 times without significant loss in reactivity. Importantly, the catalyst was highly stable under carbonylation reaction conditions, and no palladium nanoparticle was observed even after the 5th reuse.