共查询到18条相似文献,搜索用时 140 毫秒
1.
偕胺肟纤维-钯(Ⅱ)配合物的制备及其对Heck反应的催化性能研究 总被引:1,自引:0,他引:1
以聚丙烯腈纤维为基体,制备了偕胺肟纤维-钯(Ⅱ)配合物,采用FTIR、XPS等物理化学手段对其结构进行了表征.本文研究考察了该配合物在不同反应条件下对碘苯与苯乙烯的Heck反应的催化性能,结果显示:偕胺肟纤维-钯(Ⅱ)配合物在较温和的条件下即可很好的催化Heck反应,经重复使用8次后,1,2-二苯乙烯的产率仍达80%以上,并且反应结束后催化剂易于从反应体系中分离.对于其它不同底物之间的Heck反应,偕胺肟纤维-钯(Ⅱ)配合物同样显示较好的催化性能. 相似文献
2.
3.
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
4.
聚氯乙烯三乙撑四胺负载钯配合物的制备及对Heck反应的催化性能 总被引:4,自引:0,他引:4
以聚氯乙烯为原料, 通过胺化反应制得聚氯乙烯三乙撑四胺, 然后用较简单方法得到聚氯乙烯三乙撑四胺负载钯配合物(PVC-TETA-Pd), 利用XPS, TG, DTA和TEM等手段对其进行了表征. 热分析表明PVC-TETA-Pd在室温至250 ℃范围内有很好的热稳定性; TEM分析证实钯在PVC-TETA-Pd中分布比较均匀, 钯颗粒呈球形, 粒径在2~3 nm. PVC-TETA-Pd不需在惰性气体氛围中就能有效地催化丙烯酸、苯乙烯与芳基碘的Heck芳基化反应, 并且在较低的温度(40 ℃)或较少的催化剂用量(0.02%)下, 对Heck反应仍有较好的催化性能. PVC-TETA-Pd便于回收, 且有很好的重复使用性能, 对于碘苯与丙烯酸的反应, 重复使用十二次, 肉桂酸的产率仍达到80.1%. 相似文献
5.
6.
7.
MCM-41固载胺钯配合物的制备及对Heck反应催化性能的研究 总被引:1,自引:0,他引:1
以MCM-41分子筛作为固载材料, 经氨基功能化后与各种钯化合物形成一系列MCM-41载钯配合物, 采用XRD, XPS等技术对其结构及表面性能进行了表征, 研究了催化剂的制备条件等因素对催化Heck芳基化反应性能的影响; 以共轭烯烃和各种芳基碘的Heck芳基化反应考察了MCM~NH2•Pd(0, II)配合物的催化性能. 结果表明, MCM-41的结构没有被破坏, MCM~NH2载钯配合物具有较高的催化活性和立体选择性, 在较低的温度(70~90 ℃)下, 可高产率地生成一系列取代的反式产物. 相似文献
8.
9.
10.
评价了一种碳水化合物衍生的具有较大立体位阻及较三苯基膦更富电子的膦配体(甲基3-脱氧-3-二苯膦基-4,6-氧-苯次甲基-α-D-吡喃阿卓糖苷,3-MBPA)在Pd催化的Heck反应中的性能.发现在N,N-二甲基乙酰胺溶刺中K2CO3是该催化体系较适合的碱;在该配体的支持下催化剂中钯的用量可低至0.5 mo1%;可催化苯乙烯与带给电子基团的溴代芳烃及带吸电子基团的氯代芳烃发生反应,高产率地生成相应的偶联产物;反应区域选择性表明,Pd(OAc)2/3-MBPA体系在催化苯乙烯与卤代芳烃的Heck反心中并存阳离子催化途径,说明3-MBPA中的氧原了可能也参与配位;同时发现,加入助配体四丁基溴化胺(TBAB)后,可能是Br-参与配位有利于增加中性催化途径的机会而提高了反应区域选择性. 相似文献
11.
12.
13.
A new method for the preparation of SBA-15-supported palladium catalyst for Heck reaction in supercritical carbon dioxide was presented.The newly formed SBA-15-supported palladium catalyst(Ph-SBA-15-PPh3-Pd) exhibited high catalytic activity for the Heck reaction of 4-nitrobromobenzene with methyl acrylate.The catalyst can be reused several times without a loss of activity. 相似文献
14.
通过简便的方法制备了炭负载Pd/Ce双金属催化剂,利用Pd/Ce双金属催化剂的协同效应提高催化剂对Heck反应的催化效率。 以碘苯与丙烯酸的Heck芳基化反应为模型反应,研究了反应条件对催化剂催化性能的影响。 结果显示,在反应温度为130 ℃,反应时间为5 h,N,N-二甲基甲酰胺(DMF)作为溶剂和三丁胺(Bu3N)作为碱的条件下,炭负载Pd/Ce双金属催化剂对丙烯酸和碘苯的Heck芳基化反应具有良好的催化性能,产率达到70%以上。 另外,该催化剂属于非均相催化剂,催化剂易与反应溶液分离;也可以重复利用,使用3次反应产率仍达到66.9%,显示了炭负载Pd/Ce双金属催化剂良好的催化活性。 相似文献
15.
Wen‐Hao Li Cun‐Yao Li Huan‐Yan Xiong Yang Liu Wen‐Yong Huang Guang‐Jun Ji Zheng Jiang Hai‐Tao Tang Ying‐Ming Pan Yun‐Jie Ding 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2470-2475
Heterogeneous, metal, single‐site catalysts often exhibit higher catalytic performance than other catalysts because of their maximized atom efficiency of 100 %. Reported herein is a precoordination/solvothermal polymerization strategy to fabricate a stable mononuclear Pd‐metalized porous organic polymer catalyst (Pd@POP). Pd@POP was easy to use in regioselective organic reactions because the internal structure of this Pd@POP can be easily modified. The catalyst was used to solve the intractable regioselectivity problems of Heck reactions. Pd@POP‐9 can efficiently activate the ends of olefins, thereby leading to high selectivity for substitution at the external position. To understand the reason underlying the high selectivity and activity of the catalyst, the systemic characterization of Pd@POP‐9 and density‐functional theory calculations were conducted. This Heck reaction is the first to be catalyzed by a recyclable mononuclear metal catalyst with unprecedented catalytic activity and regioselectivity. 相似文献
16.
17.
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
18.
The preparation of supported Pd nanoparticles on Tris (tris(hydroxymethyl)aminomethane)- modified SiO2 gel and their catalytic application in Heck coupling are investigated. The catalyst was characterized using a combination of X-ray diffraction, transmission electron microscopy, field-emission scanning electron microscopy, and scanning electron microscopy/energy-dispersive X-ray spectroscopy. The supported Pd nanoparticles were found to be a highly active and reusable catalyst for the Heck reaction at a low Pd loading (0.02 mol%) because of stabilization by the Tris moieties. Several reaction parameters, including the type and amount of solvent, base, and temperature, were evaluated. The heterogeneity of the catalytic system was investigated using different approaches, and showed that slight Pd leaching into the reaction solution occurred under the reaction conditions. Despite this metal leaching, the catalyst can be reused seven times without significant loss of its activity. 相似文献