共查询到19条相似文献,搜索用时 171 毫秒
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无配体、在空气下Pd(OAc)_2催化的Heck反应研究 总被引:2,自引:0,他引:2
研究了无配体、空气下Pd(OAc)2催化的Heck反应.多种芳基碘化物、芳基溴化物可以与烯丙基醋酸酯、丙烯酸酯和苯乙烯等烯基化合物在Pd(OAc)2催化下发生Heck反应.该反应不需要配体的加入,在空气中就可以进行.讨论了碱、添加剂、溶剂、催化剂等因素对反应产率的影响.该反应的最优化条件是:Pd(OAc)2(5mol%)为催化剂,Ag2CO3(0.6equiv.)为添加剂,以苯或甲苯为溶剂空气中回流12h,芳基碘化物、芳基溴化物可以顺利地与烯丙基醋酸酯、丙烯酸酯、苯乙烯等烯基化合物发生Heck反应,以较高的产率得到目标产物. 相似文献
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研究了无配体、空气下Pd(OAc)2催化的Heck反应. 多种芳基碘化物、芳基溴化物可以与烯丙基醋酸酯、丙烯酸酯和苯乙烯等烯基化合物在Pd(OAc)2催化下发生Heck反应. 该反应不需要配体的加入, 在空气中就可以进行. 讨论了碱、添加剂、溶剂、催化剂等因素对反应产率的影响. 该反应的最优化条件是: Pd(OAc)2 (5 mol%)为催化剂, Ag2CO3 (0.6 equiv.)为添加剂, 以苯或甲苯为溶剂空气中回流12 h, 芳基碘化物、芳基溴化物可以顺利地与烯丙基醋酸酯、丙烯酸酯、苯乙烯等烯基化合物发生Heck反应, 以较高的产率得到目标产物. 相似文献
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无配体Pd/LDH-F催化剂在Heck和Suzuki反应中的应用 总被引:1,自引:0,他引:1
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%. 相似文献
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高活性氨基胍树脂负载Pd(0)配合物的催化性能研究 总被引:1,自引:0,他引:1
以氨基碳酸胍改性氯球为载体,与氯化钯溶液反应并还原制备氨基胍树脂负载钯(0)催化剂.对催化剂进行了FT-IR,XRD,BET,TG-DTA表征.研究了该催化剂对各种取代卤代苯与丙烯酸、苯乙烯的Heck芳基化反应催化性能.实验结果表明,该催化剂对活性(吸电子基)溴代苯和碘苯具有良好的催化活性,对含活性吸电子基的溴代苯(4-溴苯甲醛和4-溴硝基苯)于140℃时能在22min内完成Heck芳基化反应;催化剂具有较好的重复使用性能,在90℃下催化碘苯与丙烯酸的反应循环21次时仍能保持良好的催化活性.反应机理研究表明:催化反应的活性组分是可溶性钯物种;可溶性钯是由卤代苯与催化剂表面上的钯氧化加成所致. 相似文献
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以氨基碳酸胍改性氯球为载体, 与氯化钯溶液反应并还原制备氨基胍树脂负载钯(0)催化剂. 对催化剂进行了FT-IR, XRD, BET, TG-DTA表征. 研究了该催化剂对各种取代卤代苯与丙烯酸、苯乙烯的Heck芳基化反应催化性能. 实验结果表明, 该催化剂对活性(吸电子基)溴代苯和碘苯具有良好的催化活性, 对含活性吸电子基的溴代苯(4-溴苯甲醛和4-溴硝基苯)于140 ℃时能在22 min内完成Heck 芳基化反应; 催化剂具有较好的重复使用性能, 在90 ℃下催化碘苯与丙烯酸的反应循环21次时仍能保持良好的催化活性. 反应机理研究表明: 催化反应的活性组分是可溶性钯物种; 可溶性钯是由卤代苯与催化剂表面上的钯氧化加成所致. 相似文献
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Bradshaw M Zou J Byrne L Iyer KS Stewart SG Raston CL 《Chemical communications (Cambridge, England)》2011,47(45):12292-12294
Pd(II)-chitosan composite nanofibres of 62 ± 9 nm diameter are efficient catalysts for Heck cross-coupling reactions. Using a model reaction of iodo-benzene and n-butyl acrylate, we demonstrate that this material can be used as a recyclable catalytic support with a very low loading of palladium (0.17 mol% Pd). 相似文献
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Palladium catalyzed Heck reaction of 2-iodoanilines and acrylate has been developed. The palladium catalyzed Heck reaction of 2-iodoanilines can readily occur in CH3CN using Pd(OAc)2 (5.0?mol%) as catalyst, NEt3 as base under ligand-free conditions. And 2-alkenylanilines were obtained as the cross-coupling products with medium to high yield. 相似文献
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The palladium-catalyzed arylation of olefins (the Heck reaction) is one of the most versatile tools for C-C bond formation in organic synthesis. Phosphine ligands are generally used to stabilize the reactive palladium intermediates, the air-sensitivity of phosphine ligands, however, places significant limits on their synthetic applications. Recently, Yang1 and we2 have reported Heck and Suzuki reactions of highly active arenediazonium salts and halides catalyzed by air-stable monothiourea-Pd… 相似文献
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S Fujita K Yuzawa B. M Bhanage Y Ikushima M Arai 《Journal of molecular catalysis. A, Chemical》2002,180(1-2):35-42
Palladium-catalyzed Heck reaction of iodobenzene and styrene was investigated in compressed CO2 using different fluorinated phosphine compounds as ligands at a temperature of 70 °C. The reaction mixture is a single phase at 12 MPa but biphasic at 8 MPa, a little higher than the critical pressure of pure CO2 under the reaction conditions used. Although the solubility of fluorinated ligands is very high in dense CO2, they have marginal improvements in Heck conversion in this medium compared with a non-fluorinated ligand of triphenylphosphine. The activity of palladium complexes strongly depends on the kind of phosphine compound used, in the order of bis(pentafluorophenyl)phenylphosphine (III)>triphenylphosphine (I), tris(pentafluorophenyl)phosphine (IV)>diphenyl(pentafluorophenyl)phosphine (II), tris(p-fluorophenyl)phosphine (V)>tris(p-trifluoromethyl phenyl)phosphine (VI), 1,2-bis[bis(pentafluorophenyl)phosphino]ethane (VII), for the homogeneous reaction at 12 MPa. This order of effectiveness of these ligands is different from those obtained in conventional organic solvents. Hexane, toluene, ethanol, and N-methylpyrrolidone (NMP) showed maximum conversions with the ligands VI, IV, V and VII, respectively. The conversion in CO2 with the ligand III is comparable with those in polar solvents of ethanol and NMP, and larger than those in hexane and toluene in the presence of the best ligands. The dense CO2 may affect the specific activity of palladium complex catalysts and/or the reactivity of reacting species. Small quantities of fluorinated products were observed to form at high pressure of CO2 and this is direct evidence of P–C bond cleavage during Heck reaction in dense CO2. The activity of palladium complexes with those ligands is higher in more polar solvent. 相似文献
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Mesoporous Silica MCM‐41 Supported N‐Heterocyclic Carbene‐Pd Complex for Heck and Sonogashira Coupling Reactions 下载免费PDF全文
Heterocyclic carbene‐Pd complex was anchored onto the mesoporous silica MCM‐41 which exhibits high catalytic activity in Heck reaction under phosphine free reaction conditions for the reaction of iodo/bromoarenes with olefinic compounds such as butyl acrylate, isopropyl acrylate and styrene. This catalytic system also showed high activity for Sonogashira coupling reaction of various aryl halides under copper, phosphine and solvent‐free reaction conditions. The air and thermally stable catalyst were reused several times without significant loss of its activity. High efficiency of the catalyst along with its recycling ability and the rather low Pd‐loading demonstrated in both Heck and Sonogashira coupling reactions are the merits of the presented catalyst system. 相似文献
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A polymer‐supported macrocyclic Schiff base palladium complex has been synthesized. In the Heck reaction of aryl iodides and bromides with ethyl acrylate or styrene, the complex has been proved to give the corresponding products in good to excellent yields. The reaction proceeded smoothly in the presence of 0.5 mol% of catalyst in DMF within 1–4 h. Recycling studies have shown that the catalyst can be readily recovered and reused for four cycles with only a slightly decrease in its activity. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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A detailed investigation into the influence of phosphines, additives, bases and solvents on the Heck coupling reaction of 4-trifluoromethyl-1-chlorobenzene (2) is presented. It is shown that a number of catalyst systems exist for efficient cross coupling of electron-deficient aryl chlorides with various olefins. Basicity and steric demand of the ligand are two factors which determine the success of the reaction. In addition the phosphine/palladium ratio, the correct type and amount of additive, and finally the use of an appropriate base and solvent are also important. The optimised reaction conditions are applied for the arylation of styrene, 2-ethylhexyl acrylate and N,N-dimethyl acrylic amide with various aryl chlorides. 相似文献
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Zhao F Bhanage BM Shirai M Arai M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(5):843-848
The vinylation of iodobenzene with methyl acrylate has been studied with several supported palladium catalysts in N-methylpyrrolidone in the presence of triethylamine and/or sodium carbonate. The reaction can be performed in air without any solubilizing or activating ligands. It was found that significant amounts of palladium leach out into the solvent and these dissolved Pd species essentially catalyze the reaction. It is interesting, however, that almost all the palladium species in the solution can redeposit onto the surface of the supports after the reaction has been completed (at 100% conversion of iodobenzene). Thus, the catalysts were recyclable without loss of activity. The use of both inorganic and organic bases is very effective in the promotion of the palladium redeposition as well as in the enhancement of the reaction rate. For Heck reactions with bromobenzene and chlorobenzene it was found that the use of triethylamine and sodium carbonate increases the selectivity of the Heck coupling product (benzene is also produced for these two substrates), but the mixed bases do not affect the overall rate of reaction as much. 相似文献
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以聚氯乙烯为原料,用较简单的方法得到了聚氯乙烯二亚乙基三胺负载钯配合物(PVC-DETA-Pd).PVC-DETA-Pd具有较高的热稳定性,可以满足Heck反应所需要的高温条件.在110℃、氮气氛围,四丁基溴化铵(TBAB)做溶剂的条件下,PVC-DETA-Pd催化溴苯与苯乙烯的反应产率可以达到99%.PVC-DETA-Pd在多种缚酸剂的存在下均可有效地催化芳基溴的Heck反应,但在三丁胺中具有最好的效果.在适当的反应条件下,以PVC-DETA-Pd为催化剂,各种带取代基芳基溴、芳基氯均可以有效地与乙烯基化合物反应,反应产率>70%.PVC-DETA-Pd还具有较好的重复使用性能. 相似文献