共查询到19条相似文献,搜索用时 60 毫秒
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酸性沸石分子筛催化Knoevenagel综合反应 总被引:2,自引:0,他引:2
在高硅/铝比的酸性沸石分子筛HY上实现了Knoevenagel缩合反应,Bronsted酸和Lewis酸均可催化Knoevenagel缩合反应。考察了羰基化合物和活泼亚甲基化合物的反应活性顺序。结果表明,羰基化合物的羰基极化程度越高,反应越容易进程,示同于碱催化时的Knoevenagel缩合反应,活泼亚甲基化合物的活泼氢的酸性并不是影响其反应活性的重要因素。 相似文献
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新型酸性离子液体催化的 Knoevenagel缩合反应 总被引:3,自引:0,他引:3
研究了一类新型酸性离子液体催化的Knoevenagel缩合反应, 结果表明, 该催化剂适用于一系列芳香/杂环醛与α-取代活性亚甲基化合物间的反应, 反应可在室温下进行, 反应时间短且收率良好(92% ~98%). 该反应体系操作简单, 产物易分离. 提出了可能的反应机理并对机理进行了验证. 该离子液体重复使用5次后仍具有较高的反应活性. 相似文献
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通过活性炭(AC)负载壳聚糖(CS)的方法,制备了负载型的"壳聚糖/活性炭"催化剂(CS/AC)。利用FT-IR、XRD、TG-DTG、SEM、BET、元素分析等方法对催化剂进行表征,并系统研究了该催化剂在Knoevenagel缩合反应中的催化性能。结果表明,催化剂具有较好的活性,在室温无溶剂条件下,可以催化一系列芳香醛化合物与活泼亚甲基化合物进行缩合反应,产率均在80%以上;且反应体系放大100倍时,仍然保持较高的催化效率;此外,该催化剂具有较好稳定性,重复使用8次后,仍然保持较高的催化活性。 相似文献
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浸渍法制备水滑石负载氯化锌(LDH/ZnCl2)催化剂,使用傅里叶变换红外光谱(FT-IR)、扫描电镜(SEM)、比表面积(BET)、热重分析(TG)对催化剂进行表征.结果表明:在FT-IR中LDH/ZnCl2出现LDH骨架特征吸收峰和ZnCl2特征吸收峰,SEM图中LDH/ZnCl2的表面比LDH表面粗糙,可以辅证Z... 相似文献
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Qing Liu Yinfeng Han 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2033-2037
Abstract Sodium silicate pentahydrate has been utilized as an efficient catalyst for the Knoevenagel condensation of aromatic aldehydes with active methylene compounds to afford substituted olefins in yields of 80.6%~98.9% under solvent-free conditions at room temperature within a short time. The advantages of this procedure are mild reaction conditions, excellent yields, cleaner reaction profiles, and operational simplicity. GRAPHICAL ABSTRACT 相似文献
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The Knoevenagel condensation between various aldehydes (benzaldehyde, 1-naphthaldehyde, p-bromobenzaldehyde and p-methoxybenzaldehyde) and esters (ethylcyanoacetate, ethylacetoacetate and diethylmalonoester) was carried out under solvent free condition in the presence of cobalt hydroxyapatite (CoHAp), as a catalyst. Good to excellent yields (35–96%) were obtained. The catalyst is found to be superior over fluorapatite and several other heterogeneous catalysts. The catalyst can be recycled at least 3 times. 相似文献
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A facile method for Knoevenagel condensation has been developed by using Leucoemeraldine base as catalyst to give substituted alkenes in excellent yields. The recycling of the solid catalyst was investigated. 相似文献
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A study involving the scope of substrates in the Knoevenagel reaction under SFC has been conducted. Reactivity trends favored formation of the condensation product using both electron deficient and rich aryl aldehydes. A recycling study confirmed that the reaction medium could be used multiple times affording, with each run, the desired condensation product in excess of 95% conversion. 相似文献
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DaQingSHI JingCHEN QiYaZHUANG XiangShanWANG HongWenHU 《中国化学快报》2003,14(12):1242-1245
The condensation of aromatic aldehydes with acidic methylene compounds such as malononitrile, methyl cyanoacetate, cyanoacetamide, 5,5-dimethyl-1,3-cyclohexanedione,bartbituric acid and 2-thiobarbituric acid proceeded very efficiently in water in the presence of triethylbenzylammonium chloride (TEBA) and the products were isolated simply by filtration. 相似文献
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