咪唑衍生物的一锅法选择性合成

1-(2-氰乙基)咪唑与α,ω-二卤代烃、二溴苄及三溴苄选择性地发生季铵化反应,继而在碱作用下发生Hoffmann型消去反应,简便而高效地制备了3个系列咪唑衍生物:1-(ω-卤烷基)咪唑3a～3e、含中心功能基的双咪唑5a～5b和三咪唑6a～6b,并类似地制得相应的苯并咪唑衍生物7和8.     

稀土材料在多相催化中的应用研究进展概述

稀土在中国储量丰富,尤其在徐光宪等老一辈科学家不懈努力下开发了高效提纯稀土元素的有效方法,为当今的稀土性能应用研究打下了坚实的基础.稀土包括钪、钇以及镧系金属在内的17种元素,由于镧系元素最外层电子和次外层电子的结构相似([Xe]4f^n-15d^0～16s² (n=1～15)),尤其是其独特的4f电子层结构,使稀土元素具有化学性质稳定、化学价态可变、配位形式多样、总体具有Lewis酸性等特点,使其在催化领域具有广泛的应用.但稀土元素电子层结构与催化反应效果之间的关系尚未有明确的总结,因此本文从稀土材料的电子结构特点出发,综述了其在多相(热)催化领域中作为载体、Lewis酸(碱)中心以及催化助剂等方面的应用.     

改性活性炭负载FeCl_3催化一锅法合成多芳基咪唑

制备了一种新型改性活性炭负载氯化铁催化剂(MAC-Fe Cl3),通过红外光谱及等离子体发射光谱进行了表征.在MAC-Fe Cl3催化下,以乙酸铵为氮源,苯偶酰与芳醛以及伯胺作用,一锅法合成了一系列2,4,5-三芳基咪唑和1,2,4,5-四芳基咪唑.催化剂后处理简单,重复使用4次仍保持较高活性.该方法收率较高、对环境友好、操作简单.     

聚苯乙烯负载氯化铁催化一锅法合成β-氨基酮类衍生物

制备了聚苯乙烯负载型氯化铁催化剂(PS-FeCl3),并通过红外光谱、X射线衍射、扫描电子显微镜等技术手段进行了表征。 在PS-FeCl3催化下,以苯乙酮、芳醛和芳胺为原料,采用一锅法Mannich反应合成了一系列β-氨基酮衍生物。 制备的催化剂性能稳定,使用4次仍保持较高活性。     

稀土催化剂在高分子合成中的开拓应用

综述了40多年来我国在高分子合成领域中开拓应用稀土催化剂,在双烯烃、炔烃、环氧烷烃、环硫烷烃、二氧化碳共聚、丙交酯、己内酯和环碳酸酯等聚合方面取得的主要进展。     

碘作为Lewis酸催化剂在合成中的应用

碘催化的有机反应具有价廉易得、操作简单、温和、清洁、高效及高选择性等优点, 广泛应用于亲电反应、亲核反应、多组份反应以及其它涉及复杂官能团化合物的合成反应中, 在环境友好化学合成、复杂化合物合成及选择性合成领域具有应用价值.     

分子筛稳定的Lewis酸稀土中心在醛自缩合反应中的应用

羟醛缩合是重要的C–C键偶联反应,可以增长碳链,降低O/C比,用于生产很多大宗化学品,在生物质转化和生物油升级中广受关注.本文以丙醛分子自缩合反应作为模型反应,对比研究了稀土分子筛和稀土氧化物在醛自缩合反应中的催化性能,发现稀土分子筛的活性远高于稀土氧化物,其中Y/Beta活性最佳,并且具有良好的循环性能.随后采用程序...     

木质素及其衍生物负载金属催化剂在有机合成中的应用研究进展

碳中和发展理念的提出使得生物质基催化剂的关注度不断提高,将木质素作为过渡金属催化剂的载体来制备非均相催化剂应用于有机合成领域,可以极大地提高木质素的利用价值.木质素结构中广泛存在的含氧官能团为金属催化剂的负载提供了多种结合位点,通过物理吸附/沉积、离子交换以及与羟基官能团通过静电络合可以有效地捕获金属粒子.首先介绍了木质素的结构,然后介绍了制备非均相催化剂的方法,重点介绍了木质素及其衍生物负载金属催化剂催化点击反应、Glaser反应、Huisgen [3+2]环加成反应、Heck反应、Suzuki反应、Sonogashira反应、Stille偶联反应、迈克尔加成/脱水串联反应、亲电开环反应、Fridel-Crafts型反应及乙烯聚合反应等,并对存在的问题和发展趋势进行了展望.     

高岭土负载SO2-4/ZrO2-TiO2催化剂的制备及其在缩酮合成中的应用

以经H2SO4处理焙烧的高岭土为载体,制备了以其负载的SO4(2-)/ZrO2-TiO2固体酸催化剂.用FT-IR、XRD和NH3-TPD等测试技术表征了催化剂的微观结构及酸强度,考察了对环己酮乙二醇缩酮反应的催化活性及稳定性.结果表明,酸化处理使高岭土表面酸量增加,但酸强度变化不大,而其负载SO4(2-)/ZrO2-TiO2后,经500℃焙烧3 h其酸量及酸强度显著升高.环己酮用量为0.2 mol、乙二醇0.24 mol、催化剂1.2 g、带水剂环己烷15 mL,回流反应70 min后,缩酮收率可达96.8%,催化剂重复使用5次收率保持在90%以上.     

碘作为Lewis酸催化剂在合成中的应用进展

碘催化的有机反应具有价廉易得、操作简单、温和、清洁、高效及高选择性等优点,广泛应用于亲电反应、亲核反应、多组份反应以及其它涉及复杂官能团化合物的合成反应中,在环境友好化学合成、复杂化合物合成及选择性合成领域具有应用价值.     

One‐pot and Environmentally Friendly Synthesis of New Spiroindolones Using Functionalized Multiwall Carbon Nanotubes as Powerful Catalyst

Multiwall carbon nanotubes were functionalized and then used as powerful nanocatalyst for the one‐pot, three‐component synthesis of new spiroindolones. Functionalized multiwall carbon nanotubes (FMWCNTs) showed a good catalytic ability and recyclability in the current reaction. The present strategy offers some interesting advantages such as simplicity, high yields of products, and non‐toxic nature.     

Efficient Multi‐component Synthesis of Highly Substituted Imidazoles Utilizing P2O5/SiO2 as a Reusable Catalyst

Phosphorus pentoxide supported on silica gel (P₂O₅/SiO₂) has been used as an efficient and reusable catalyst for the one‐pot pseudo four‐component synthesis of 2,4,5‐trisubstituted imidazoles from benzil or benzoin, aldehydes, and ammonium acetate. It was also used for four‐component preparation of 1,2,4,5‐tetrasubstituted imidazoles from benzil or benzoin, aldehydes, primary amine, and ammonium acetate under thermal solvent‐free conditions. The remarkable features of this new procedure are high conversions, cleaner reaction, simple experimental and work‐up procedures and also the catalyst can be easily separated from the reaction mixture and reused several times without any loss of its activity.     

An Environmentally Benign Water Promoted Catalyst Free Highly Efficient,One‐pot Synthesis of 2‐Imino‐4‐thiazolidinone

A practical and efficient protocol has been developed for the synthesis of 2‐imino‐4‐thiazolidinone through a unique one pot three‐component reaction of variety of amines, isothiocyanate and ethylbromoacetate in water. The method is free of catalyst and other toxic solvents, has shorter reaction times, high‐yielding, effortlessness in isolation of product, making it more eco‐friendly process, and suitable for large scale operation.     

Alumina Supported 12‐Tungstophosphoric Acid as an Efficient and Reusable Catalyst for Synthesis of 1,5‐Benzodiazepines

Alumina supported 12‐tungstophosphoric acid catalyzes efficiently the reaction of o‐phenylenediamine with ketones under solvent‐free condition to afford the corresponding 1,5‐benzodiazepines in good to excellent yields. The catalyst can be recovered and reused.     

A Simple and Efficient One‐pot Synthesis of 1,4‐dihydropyridines Using Nano‐WO3‐ supported Sulfonic Acid as an Heterogeneous Catalyst under Solvent‐free Conditions

Nano‐tungsten trioxide‐supported sulfonic acid (n‐WSA) was found to be an effective heterogeneous cat‐ alyst for the one‐pot reaction of aromatic aldehydes, β‐dicarbonyl compounds and ammonium acetate to afford 1,4‐dihydropyridine derivatives in good to excellent yields. The other main advantages of the pres‐ ent method are short reaction times, simple workup, ease in purification and environmentally benign methodology. The reaction conditions were optimized employing Response Surface Method technique (Central Composite Design (CCD)) which is economically considerable because of the minimum number of experiments required to evaluate the effects of multiple parameters on the response.     

An Efficient,Multicomponent, One‐pot Synthesis of Tetra Substituted Pyrans in Water

A new and environmentally benign multi‐component synthesis of tetra substituted 4H‐pyran derivatives is developed via the one‐pot reaction of an aromatic aldehyde, malononitrile, and 1,3‐diketone in the presence of NaOH with water as the solvent at RT. The reaction is efficient and affords excellent yields of the products.     

Carbon-Based Solid Acid as An Efficient and Reusable Catalyst for One-Pot Synthesis of Tetrasubstituted Imidazoles under Solvent-Free Conditions

Carbon‐based solid acid catalyst was found to be highly efficient, eco‐friendly and recyclable heterogeneous catalyst for the multicomponent reaction of benzil, aromatic aldehyde, primary amine and ammonium acetate, giving rise to 1,2,4,5‐tetrasubstituted imidazoles in good to excellent yields. The present methodology offers several advantages, such as high yields, short reaction time, mild reaction condition and a recyclable catalyst with a very easy work up.     

Silica‐supported Perchloric Acid Catalyzed One‐pot Synthesis of 1,4‐Dihydropyridines

An environmentally friendly and highly efficient procedure for the preparation of 1,4‐dihydropyridines by the reaction between α,β‐unsaturated aldehydes, aromatic amines and β‐keto esters in the presence of silica supported perchloric acid is described.     

Simple and Efficient Method for the Synthesis of Highly Substituted Imidazoles Catalyzed by Benzotriazole

Benzotriazole is an efficient, readily available, and simple catalyst for the synthesis of 2,4,5‐trisubstituted imidazoles in high yields from 1,2‐diketones and aldehydes in the presence of NH₄OAc via multi‐components reaction. The significant features of this one‐pot procedure are very simple operation, easy work‐up and purification of products.