共查询到20条相似文献,搜索用时 109 毫秒
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以磺酸功能化咪唑离子液体为催化剂,以3-羟基丙酸甲酯为原料,采用自身酯交换法合成了具有生物可降解性能的聚羟基脂肪酸酯.系统考察了离子液体种类、反应温度以及聚合反应时间对反应性能的影响,同时采用红外、核磁、热分析等手段对产物进行表征.研究结果表明:阴离子为CF3SO-3的磺酸功能化离子液体在120℃的低温下催化聚合反应所得聚酯Mw可达10 159,收率82.1%;通过水洗方法可有效去除产物中的离子液体催化剂,从而避免催化剂污染产物. 相似文献
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设计新型液液两相催化体系:π配体离子液体 总被引:6,自引:0,他引:6
π配体催化剂与离子液体体系相结合有助于解决反应效率、产物分离和催化剂循环等一系列均相催化体系不易解决的难题. 近几年相关的研究逐渐深入,由简单地使用离子液体作为π配体催化反应的介质向利用离子液体自身结构的方向发展,相继出现了几类不同的研究思路. 例如,利用π配体催化剂与离子液体形成络合物,使用离子型π配体改善催化剂在离子液体中的溶解性,以及合成功能化阳离子或功能化阴离子的π配体离子液体. 本文结合这几类离子液体化学键联π配体(简称π配体离子液体)的研究进展,从离子液体功能化设计的角度探讨了π配体离子液体的合成思路,为设计具有更好催化性能的功能化离子液体体系提供借鉴. 相似文献
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SBA-15 固载离子液体功能化脯氨酸的制备及其催化 Knoevenagel 缩合反应 总被引:3,自引:0,他引:3
以 L-脯氨酸为原料合成了离子液体功能化脯氨酸前驱体 (IL-Pro), 并将其固载到 SBA-15 介孔分子筛上, 制得 IL-Pro/SBA-15 催化剂. 用红外光谱、热重、N2 吸附-脱附、X 射线衍射和透射电镜等手段表征了 IL-Pro/SBA-15 催化剂, 并考察了该催化剂在 Knoevenagel 缩合反应中的催化性能. 结果表明, 固载离子液体功能化脯氨酸没有破坏 SBA-15 的有序介孔结构, 但孔体积、孔径和比面表积有所下降; IL-Pro/SBA-15 的失重峰在 250~360 oC (峰值为 310 oC). 在以苯甲醛和丙二腈为底物的 Knoevenagel 反应中, IL-Pro/SBA-15 催化剂表现出较高的活性, 缩合产物收率高达 94%; 经简单分离后催化剂可重复使用 7 次以上而活性基本保持不变. 相似文献
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采用溶胶-凝胶法制备的离子液体功能化的二氧化硅对于杂多酸是一种可行的载体,三种商用杂多酸成功的负载在离子液体功能化的二氧化硅上作为醇氧化的催化剂.利用FTIR、XRD、XPS对该种负载离子液相催化剂进行了表征.基于磷钨酸的负载离子液相催化剂活性最好,高产率(大部分>93%)的得到了相应的羰基化合物.且该催化剂经过简单的... 相似文献
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On Regioselectivity of Aldol Condensation of Aromatic Aldehydes with Borate Complex of Acetylacetone
While cinnamoyl acetone 1 is obtained in good yield by a condensation of 3 molar excess of a borate complex of acetylacetone with benzaldehyde, products of Knoevenagel condensation 2 are predominantly obtained with furfural and 5-substituted furfurals. Cinnamoyl acetone 1 can be further condensed with furfural to form unsymmetrical curcuminoid 5. Compound 2a does not produce any new products under the same conditions. Compounds 3 and 5 are good inhibitors of growth of protozoan Trichomonas vaginalis. 相似文献
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MgC2O4/SiO2 catalyzes the efficient Knoevenagel condensation of aldehydes with active methylene compounds in solvent-free conditions under microwave irradiation to give alkenes derivatives in excellent yields. MgC2O4/SiO2 can be reusable for Knoevenagel condensation. However, ketones have been found to be unsatisfactory in the reaction under the same conditions. 相似文献
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The reaction rate of Knoevenagel condensation can be dramatically enhanced by irradiating the reaction mixture containing an aldehyde, diethyl malonate, P2O5, piperidine, and chlorobenzene with a commercial microwave oven. Six Knoevenagel condensation products were synthesized within 5–15 min in good yields. 相似文献
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《应用有机金属化学》2017,31(11)
Fe3O4 magnetic nanoparticles (MNPs) were obtained using a reduction–precipitation method. These MNPs were modified with cysteamine hydrochloride. This catalyst was characterized using a number of physicochemical measurements. The Fe3O4–cysteamine MNPs, as an efficient and heterogeneous catalyst, were successfully used for Knoevenagel condensation under mild conditions. The activity of this nanomagnetic catalyst in the Knoevenagel condensation of aromatic aldehydes and malononitrile is described. Easy preparation of the catalyst, easy work‐up procedure, excellent yields and short reaction times are some of the advantages. 相似文献
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《Green Chemistry Letters and Reviews》2013,6(1):17-21
Abstract Alum (KAl(SO4)2·12H2O) is an inexpensive, efficient, and non-toxic catalyst used for the synthesis of 5-arylidine-2,4-thiazolidinediones by the Knoevenagel condensation of aromatic aldehydes with 2,4-thiazolidinedione in aqueous media at 90°C. This method affords the 5-arylidine-2,4-thiazolidinediones in short reaction times, high yields, and green aspects by avoiding toxic catalysts and hazardous solvents. 相似文献
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P. Margaretha F. P. Schmook H. Budzikiewicz O. E. Polansky 《Monatshefte für Chemie / Chemical Monthly》1968,99(6):2539-2548
The reaction of malonylchloride with ethylene glycol or dithioglycol at low temperatures and high dilution leads to cyclic condensation products of 2∶2 composition, of which the first one reacts with aldehydes to give alkenes (Knoevenagel condensation). On the other hand, malonyl chloride and pinacol react under the same conditions to give a linear oligomeric condensation product. The Knoevenagel condensation products are electrically neutral organic Lewis acids (pK′ L -values: 8.35 and 7.85). Mass-spectra, NMR-, UV- and IR-spectra were employed for structural determinations. 相似文献
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《Journal of Coordination Chemistry》2012,65(21):3808-3816
A two-dimensional zinc phosphite-phosphate [C3H6(OH)NH3][Zn2(HPO3)(PO4)] (1) was hydrothermally synthesized with 2-hydroxypropylammonium cation as the structure-directing agent. This compound has been characterized by single-crystal X-ray diffraction, IR spectroscopy, and powder X-ray diffraction (XRD). Its microporous framework is constructed by ZnO4, PO4, and HPO3 tetrahedral building blocks with 3, 4, and 6-ring channels. With 1 as base catalytic support, the Knoevenagel condensation reaction of benzaldehyde and ethyl cyanoacetate gives a yield of 59%. 相似文献
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《Comptes Rendus Chimie》2015,18(2):223-232
Amine functionalized silica coated Fe3O4 nanoparticles (SiO2@MNP-A) were successfully prepared as a novel heterogeneous amine. The catalyst was characterized by XRD, FT-IR, TEM, magnetic measurement, elemental analysis and was found to be a magnetically separable and highly active catalyst for ambient Knoevenagel condensation of aromatic aldehydes and α-aromatic (heteroaromatic or polyaromatic)-substituted methylene compounds in water under ultrasonic irradiation to afford the corresponding products in good to excellent yields. Very interestingly, SiO2@MNP-A successfully catalyze the reaction of the non-cyano substituted compound with benzaldehyde to achieve a key intermediate for the preparation of Atorvastatin calcium in green and atom-economic manner. In addition, the catalyst SiO2@MNP-A can be reused for 8 times without any obvious loss of its activity. The role of ultrasonication in the Knoevenagel condensation was also discussed with the assistance of UV–vis spectrometry. 相似文献