共查询到20条相似文献,搜索用时 125 毫秒
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合成了新型的手性铝/锌杂双金属复合物(R,S,S)-3,3'-二[(N-二苯基脯氨醇)甲基]-2,2'-二羟基-1,1'-联萘酚铝/锌复合物(ZABDP).在催化芳香酮与芳香醛的羟醛缩合(Aldol)反应中,该复合物中的铝作为路易斯酸活化醛,锌的烷氧化物作为Br?nsted碱,使苯乙酮形成活性锌的烯醇化物,2种金属的应用使得芳香醛与芳香酮的直接不对称Aldol反应顺利进行,反应的对映选择性最高达90%,产率最高达99%. 相似文献
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自从L-脯胺酰胺被发现能高效催化不对称aldol反应以来,手性氨基酸酰胺催化剂的设计及不对称催化研究一直受到关注。特别是“烯胺-双氢键”模型的提出为设计新型有机小分子催化剂提供了理论依据,使催化剂的结构设计趋于多样化。本文重点总结了含有单氢键给体、双氢键给体及多氢键给体的氨基酸酰胺催化的不对称催化反应,主要包括不对称直接aldol反应、Mannich反应、Michael加成反应、环加成反应、串联环化反应、Biginelli反应等方面的研究进展。 相似文献
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介绍了一个以(S)-脯氨酸为有机小分子催化剂的不对称交叉aldol缩合反应实验。在(JS)-脯氨酸催化下,对硝基苯甲醛和丙酮发生aldol缩合反应,生成具有光学活性的β-羟基酮产物,并通过谱学方法和比旋光度的测定进行表征。讨论了该实验在高年级本科生科研训练教学工作中的实践效果。 相似文献
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C. Marco E. P. Collar S. Areso J. Ma. García‐Martínez 《Journal of Polymer Science.Polymer Physics》2002,40(13):1307-1315
This study investigates the role played by two different interface agents on the basis of atactic polypropylene in the continuous/disperse phase polypropylene/polyamide‐6 (PP/PA6) system. The two agents used were obtained at the authors' laboratories from an atactic polypropylene byproduct derived from industrial polymerization reactors and consist of two grafted polymers containing either succinic anhydride (a‐PP‐SA) or both succinyl‐fluorescein and succinic anhydride grafted groups (a‐PP‐SF/SA). The role of these grafted polymers as compatibilizers in PP/PA6 polymer blends has been confirmed in previous investigations on the basis of their macroscopic behavior. This work investigates the thermal study of these blends where polypropylene acts as the polymer matrix and polyamide as the dispersed phase. Under isothermal conditions, thermal analysis agrees with the changes in the overall system behavior caused by the presence of the interface agents. These aspects were confirmed by polarized light microscopy that showed the morphology of the blends before and after modification with a‐PP‐SA or a‐PP‐SF/SA. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1307–1315, 2002 相似文献
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镍基催化剂的制备、表征及选择加氢性能 总被引:10,自引:0,他引:10
研究了溶胶-凝胶-超临界流体干燥法(sol-gel-SCFD)和浸渍法(IM)制备的SiO2负载镍催化剂的顺酐液相加氢性能,并用XRD、TPR、IR等手段对催化剂的体相和表面结构进行了表征.结果表明: 1) Sol-Gel-SCFD法制备的催化剂其体相和表面结构与镍含量有关,当镍含量 < 30%(质量分数)时,NiO主要以簇团形式存在;随镍含量增高到50%,过量的NiO以微晶态存在并覆盖部分NiO簇团.顺酐(MA)加氢产物有丁二酸酐(SA)和γ-丁内酯(γ-BL),它们的选择性随镍含量增加呈规律性变化;在镍含量为30%的催化剂上γ-BL选择性呈现最大值. 2) IM法制备的催化剂其体相和表面结构与镍含量无关,当镍含量在6%~30%范围内变化时,NiO都以结晶态存在,MA加氢产物为SA; NiO与SiO2的相互作用随镍含量增加而减弱,SA的选择性不变. 相似文献
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Maciej Podgrski Sudheendran Mavila Sijia Huang Nathan Spurgin Jasmine Sinha Christopher N. Bowman 《Angewandte Chemie (International ed. in English)》2020,59(24):9345-9349
The reaction of thiols and anhydrides to form ring opened thioester/acids is shown to be highly reversible and it is accordingly employed in the fabrication of covalent adaptable networks (CANs) that possess tunable dynamic covalent chemistry. Maleic, succinic, and phthalic anhydride derivatives were used as bifunctional reactants in systems with varied stoichiometries, catalyst, and loadings. Dynamic characteristics such as temperature‐dependent stress relaxation, direct reprocessing and recycling abilities of a range of thiol–anhydride elastomers, glasses, composites and photopolymers are discussed. Depending on the catalyst strength, 100 % of externally imposed stresses were relaxed in the order of minutes to 2 hours at mild temperatures (80–120 °C). Pristine properties of the original materials were recovered following up to five cycles of a hot‐press reprocessing technique (1 h/100 °C). 相似文献
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The pseudo-boehmite derived alumina supported metal(Cu,Co and Ni) catalysts prepared by the impregnation method were investigated in hydrogenation of maleic anhydride(MA) to succinic anhydride(SA) and γ-butyrolactone.The catalysts were characterized by ICP-AES,N_2 adsorptiondesorption,XRD,H_2-TPR,CO-TPD,dissociative N_2O adsorption and TEM and the results showed that the alumina possessed mesoporous feature and the metal species were well dispersed on the support.Compared to Cu/Al_2O_3 and Co/Al_2O_3,Ni/Al_2O_3 exhibited higher catalytic activity in the MA hydrogenation with 92%selectivity to SA and nearly 100%conversion of MA at 140 °C under 0.5 MPa of H_2 with a weighted hourly space velocity of 2 h ~1(MA).The stability of Ni/Al_2O_3 catalyst was also investigated. 相似文献
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Preparation of poly(glycidylmethacrylate‐divinylbenzene) weak acid cation exchange stationary phases with succinic anhydride,phthalic anhydride,and maleic anhydride for ion chromatography 下载免费PDF全文
Junwei Liu Yong Wang Shuchao Wu Peimin Zhang Yan Zhu 《Journal of separation science》2016,39(15):2970-2977
In this work, poly(glycidylmethacrylate‐divinylbenzene) microspheres were prepared and applied for the preparation of weak acid cation exchange stationary phases. Succinic anhydride, phthalic anhydride, and maleic anhydride were selected as carboxylation reagents to prepare three weak acid cation exchangers by direct chemical derivatization reaction without solvent or catalyst. The diameters and dispersity of the microspheres were characterized by scanning electron microscopy; the amount of accessible epoxy groups and mechanical stability were also measured. The weak acid cation exchangers were characterized by Fourier transform infrared spectroscopy; the content of carboxyl groups was measured by traditional acid base titration method. The chromatographic properties were characterized and compared by separating alkali, alkaline earth metal ions and ammonium and polar amines. The separation properties enhanced in the order of succinic anhydride, phthalic anhydride, and maleic anhydride modified poly(glycidylmethacrylate‐divinylbenzene) cation exchangers. 相似文献
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RuCl3/PPh3催化顺酐加氢为琥珀酸酐的反应机理研究 总被引:2,自引:0,他引:2
利用原位^31P NMR,IR技术跟踪了RuCl3/PPh3催化顺酐加氢过程,并考察了酸碱的添加对反应的影响。根据实验结果,提出了在RuCl3/PPh3催化剂体系作用下,顺酐均相加氢生成琥珀酐的反应历程:RuCl3/PPh3在反应体系中生成活性物种RuHCl(PPh3),顺酐以C=C双键与Ru-H活性物种配位生成配合物,此配合物分子内氢转移,形成金属烷基化物,该化合物再与氢进行氧化加成,还原脱出产物琥珀酸酐和Ru-H活性物种,完成整个催化循环。 相似文献
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