共查询到19条相似文献,搜索用时 125 毫秒
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氟喹诺酮作为钯催化Heck反应有效配体的研究 总被引:3,自引:2,他引:1
研究了氟喹诺酮作为钯催化Heck反应的有效配体. 碘苯、溴苯和其它芳基卤衍生物与丙烯酸丁酯、苯乙烯等取代乙烯类化合物在钯和氟喹诺酮的催化下发生Heck反应. 讨论了配体、催化剂用量、碱和溶剂对Heck反应产率的影响. 该反应的最优化条件是: 钯源为Pd(OAc)2 (0.1 mol%), 诺氟沙星作为配体(0.2 mol%), K2CO3作为碱, DMA作为溶剂, 取代碘苯及溴苯和它们的衍生物与丙烯酸丁酯、苯乙烯等乙烯基化合物的反应均可以得到高收率的目标偶联产物. 相似文献
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利用X-光电子能谱、紫外-可见光谱、电子显微镜等技术研究了硅胶负载的聚乙烯吡啶-聚[苯乙烯-顺丁烯二酸]-钯催化剂的结构.发现催化剂中活性组分除钯(0)外,还存在少量钯(Ⅱ).第二种高分子的存在可以影响钯(Ⅱ)的相对含量.催化剂中钯以很小的粒子均匀分布在载体上,因此具有良好的催化加氢性能. 相似文献
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在室温下,烯基膦氧化合物能够快速地替换掉零价钯配合物Pd(PEt_3)_4中的两个膦配体,高产率地合成对应的烯基膦氧配位的钯配位化合物3a~3e.烯基膦氧配位的镍和铂配合物3f和3g也能够通过类似的反应方法获得. 3e能够与HOAc反应缓慢地释放出烯基膦氧化合物;在相似的条件下再加入2倍量的PEt_3,反应能够进行彻底,并缓慢沉淀出一个季磷盐4.与Pd(PEt_3)_4类似, 3d也能够与苯乙炔和亚磷酸二乙酯发生钯氢化反应生成对应的乙烯基-Pd-磷酰基配位化合物,但是反应速度相对比较慢,该结果说明,在钯催化炔烃膦酰化反应中,生成的烯基膦氧化合物将一定程度上抑制催化循环中钯氢化环节的发生.所合成的配位化合和季磷盐4都经过核磁表征,其中两个化合物的分子结构还经过X射线衍射技术确认. 相似文献
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前文报道了聚[(苯乙烯)联吡啶]钯(0)催化剂在芳基碘化物乙烯基化反应中的应用,其催化剂的活性较高,但连续使用三次后,活性明显降低.本文继续报道能用于芳基碘化物乙烯基化反应的高分子负载钯催化剂的合成和应用.据文献报道能用于芳基碘化物乙烯基化的高分子负载钯催化剂,都是通过多步反应将配体导入聚苯乙烯骨架上合成的,操作比较复杂.为了简化催化剂的制备方法,我们探索了用聚(4-乙烯基吡啶)作高分子载体的可能性.将4 乙烯基吡啶与苯乙烯共聚,加入2%二乙烯基苯作交联剂,生成的共聚物用醋酸钯处理后,加氢化铝锂还原,得到每克含钯7.0mg、氮33.7mg的催化剂,并研究了它在芳基碘化物与苯乙烯、丙烯酸和丙烯酰胺的反应中的催化性能. 相似文献
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The ethylenediamine-functionalized resin-supported Pd(0)complex was prepared from PdCl_2 and ethylenedia-mine-functionalized chloromethylated polystyrene,followed by reduction with KBH_4.The complex was character-ized by FT-IR,XRD,BET,SEM and EDS.The resin-supported catalyst exhibited high catalytic activity in theHeck reaction and could be reused up to 17 times in NMP or 16 times in DMF at 90 ℃ in the Heck reaction of io-dobenzene with acrylic acid.The leaching investigation disclosed that the palladium leaching was caused by the in-teraction of iodobenzene with the metal Pd(0)on supported catalyst.The leached palladium species in filtrate wasvery stable and could be reused five times after the solid catalyst was filtered off.A cross-transfer test in recyclingin the presence of additional carbon disclosed that the soluble leached palladium species had much higher catalyticactivity than supported and/or adsorbed palladium in solid-solution heterogeneous Heck reaction. 相似文献
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《应用有机金属化学》2017,31(4)
A convenient, mild and cost‐effective synthesis of palladium nanoparticles stabilized by a mixture of natural carbohydrate beads (gum arabic and pectin) as a new bio‐organometallic catalyst is reported. Powder X‐ray diffraction, transmission and scanning electron microscopies and energy‐dispersive X‐ray and UV–visible spectroscopies were employed to characterize this supported Pd nanoparticles/gum arabic/pectin catalyst. The nanocatalyst exhibited efficient activity in Mizoroki–Heck cross‐coupling reactions between various aryl halides and n ‐butyl acrylate under solvent‐free conditions. The catalyst can easily be recovered from the reaction system and reused several times with high yields. The products were obtained in short reaction times with excellent yields. 相似文献
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Silica–acetylacetone‐supported palladium nanoparticles as an efficient and reusable catalyst in the Heck–Mizoroki C–C cross‐coupling reaction 下载免费PDF全文
The preparation of palladium nanoparticles supported on acetylacetone‐modified silica gel and their catalytic application for Heck olefination of aryl halides were investigated. The catalyst was characterized using X‐ray diffraction, X‐ray photoelectron spectroscopy, and transmission and scanning electron microscopies. The supported palladium nanoparticles are demonstrated to be a highly active and reusable catalyst for the Heck reaction. Several reaction parameters, including type and amount of solvent and base, were evaluated. The heterogeneity of the catalytic system was investigated with results indicating that there is a slight palladium leaching into the reaction solution under the applied reaction conditions. Despite this metal leaching, the catalyst can be reused nine times without significant loss of catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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The guanidine‐functionalized resin‐supported Pd(0) catalyst [GDR·Pd(0)] is highly active in Heck reaction of aryl bromides with acrylic acid or styrene without the need to exclude air. The catalyst can be recycled at least 9 times without significant loss of activity in N‐methyl‐2‐pyrrolidone at 140 °C. The Heck reaction proceeds homogeneously with dissolved palladium species and the dissolved active palladium species can redeposit onto the surface of catalyst in the reaction. The XRD peak shifting of Pd phases in the catalyst provides the evidence for the re‐deposition of the active palladium species. 相似文献
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Mansur B. Ibrahim Rami Suleiman Mohammed Fettouhi Bassam El Ali 《Transition Metal Chemistry》2017,42(1):1-8
A palladium(II)-bis(oxazoline) complex supported on silica (Pd-BOX-Si) was prepared, characterized and applied as a catalyst in Mizoroki–Heck cross-coupling reactions. The bis(oxazoline) (BOX) ligand has a hydroxyl group that can be anchored to 4-benzyl chloride-functionalized silica gel, followed by the coordination of palladium(II) chloride. The catalytic activity and the recyclability of Pd-BOX-Si have been investigated in the production of cinnamic acid derivatives via Mizoroki–Heck coupling reactions of acrylates with aryl halides; The Pd-BOX-Si catalyst demonstrated excellent catalytic activity. Characterization of the recycled Pd-BOX-Si catalyst revealed its good stability under the reaction conditions employed. 相似文献