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41.
Yoshihiro Kubota Yusuke Nishizaki Hisanori Ikeya Masami Saeki Tetsunari Hida Sachiko Kawazu Michitaka Yoshida Hidekazu Fujii Yoshihiro Sugi 《Microporous and mesoporous materials》2004,70(1-3):135-149
Two types of organic–inorganic hybrid base catalysts are prepared. Organic-functionalized molecular sieves (OFMSs), particularly “amine-immobilized porous silicates”, are designed based on common idea to immobilize catalytic active sites on silicate surface. Silicate–organic composite materials (SOCMs), such as “ordered porous silicate–quaternary ammonium composite materials”, are the precursors of ordered porous silicates obtained during the synthesis. Both the OFMS and the SOCM are used as the catalysts for Knoevenagel condensation. Among the OFMSs, there is clear tendency that the use of molecular sieve with larger pore volume and/or surface area gives the product in higher yield. Aminopropylsilyl (AP)-functionalized mesoporous silicates such as AP-MCM-41 gives the product in high yield under mild conditions. No loss of activity is observed after repeated use for three times. The SOCMs are also active for the same reaction. The precursors of the mesoporous silicates are more active than those of microporous silicates. This material can be repeatedly used without significant loss of activity. High activity is not due to the leached species. The active sites of the SOCM catalysts are considered to be SiO− moieties located on the pore-mouth. Activity of the SOCM increases when the reaction is carried out without solvent, whereas decrease in activity of the OFMS is observed in the solvent-free system. 相似文献
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3 取代苯基 5 羟基 5 三氟甲基异口恶唑啉是合成具有异口恶唑结构的原卟啉原氧化酶抑制剂类除草剂的重要中间体。通过以下途径制得4个具有不同取代基的异口恶唑啉中间体:首先,在回流状态,n(甲醇钠)∶n(取代苯乙酮)=2∶1的甲醇钠存在下,取代苯乙酮与三氟乙酸乙酯缩合得到取代苯基 4,4,4 三氟 1,3 丁二酮;后者可在室温下,于二氯甲烷溶剂中,用氯化硫酰氯化,在侧链上引入氯原子;最后,以乙酸作溶剂,回流下,具有不同取代基的苯基 1,3 丁二酮与盐酸羟胺闭环得到产物。反应总收率大于95%。产品结构经质谱、核磁共振氢谱、碳谱确认正确。 相似文献
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对三阳离子交换树脂在乙醛酸与尿素缩合反应中的催化活性进行了研究。实验得到其最佳反应条件为:尿素与乙醛酸摩尔比4:1,反应温度70℃,反应时问8h。在此条件下,尿囊素产率达到69.6%。实验结果还表明,阳离子交换树脂催化剂优于HZSM-5分子筛催化性能。 相似文献
46.
Edward J. Rode Paul E. Gee Linda N. Marquez Tetsuji Uemura Mohammad Bazargani 《Catalysis Letters》1991,9(1-2):103-113
Alkali metal zeolites and metal oxides were used for the aldol condensation of n-butanal to 2-ethyl-2-hexenal. The order of activity at 150 °C and 1 atm. was: CsNaY > NaY > LiNaY > MgO >Al2O3. Selectivity to 2-ethyl-2-hexenal was 100% for both pure and mixed isomer feed. Infrared spectroscopic studies showed that stable catalysts were produced by propene pretreatments which blocked Lewis acid sites. Adsorption of ammonia and carbon dioxide on CsNaY during aldol condensation of n-butanal causes a decrease in rate. This result, along with the order of activity, suggests that the presence of both acid and basic sites produce higher activity than strongly basic MgO.Work performed at San Jose State University. 相似文献
47.
富氮生物质热解气的分级冷凝特性研究 总被引:1,自引:0,他引:1
采用固定床热解反应系统对稻壳负载尿素进行了热解耦合分级冷凝的研究,实验采用三级冷凝的方法,对比了热解温度(400、500、600℃)和冷凝温度(30、60、90℃)对产物分布和富集的影响,研究了生物质富氮热解和分级冷凝的机理。结果表明:富氮热解促进了Maillard反应产生含氮杂环物;分级冷凝富集规律明显,一级生物油富集了高露点的酚类,二级生物油富集了低露点的含氮杂环物;提高热解温度可以增加二级生物油中含氮杂环物的含量和降低二级生物油水分含量,热解温度为500℃时,液体产物产率和酚类产物产率最大;提高冷凝温度能增强各级油组分的富集效果,并降低一级生物油水分含量,一级冷凝温度为90℃时,水分几乎完全富集在第二级中,且一级生物油酚类产物含量最高。 相似文献
48.
探讨了水解缩聚、环体开环共聚两种合成方法制备高粘度二甲基二苯基室温硫化硅橡胶的可行性,讨论了工艺过程对产品性能的影响因素。 相似文献
49.
O. Mukbaniani M. Matsaberidze M. Karchkhadze L. Khananashvili V. Achelashvili 《应用聚合物科学杂志》2002,84(7):1409-1417
The hydrolytic condensation of 1,3‐dichloro‐1,3‐disila‐1,3‐diphenyl‐2‐oxaindane under neutral conditions produced α'ω‐dihydroxy‐1,3‐disila‐1,3‐diphenyl‐2‐oxaindane (polymerization degree ≈ 4). The homofunctional condensation of α'ω‐dihydroxy‐1,3‐disila‐1,3‐diphenyl‐2‐oxaindane in a toluene solution and in the presence of activated carbon was performed, and dihydroxy‐containing oligomers with various degrees of condensation were obtained. Through the heterofunctional condensation of dihydroxy‐containing oligomers with α'ω‐dichlorodimethylsiloxanes in the presence of amines, corresponding block copolymers were obtained. Gel permeation chromatography, differential scanning calorimetry, thermomechanical analysis, thermogravimetry, and wide‐angle roentgenography investigations were carried out. Differential scanning calorimetry and roentgenography studies of the block copolymers showed that their properties were determined by the ratio of the lengths of the flexible and linear poly(dimethylsiloxane) and rigid poly(1,3‐disila‐1,3‐diphenyl‐2‐oxaindane) fragments in the macromolecular chain. At definite values of the lengths of the flexible and rigid fragments, a microheterogeneous structure was observed in the synthesized block copolymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1409–1417, 2002; DOI 10.1002/app.10335 相似文献
50.