酸催化甘油与苯甲醛缩合制备六元环缩醛

比较了对甲苯磺酸(PTSA)、磷钨酸(PWA)、KHSO4和FeCl3催化对甘油与苯甲醛的缩合反应收率,及对产物中六元环缩醛5-羟基-2-苯基-1,3-二氧六环(1)与五元环缩醛4-羟甲基-2-苯基-1,3-二氧五环(2)比例的影响。当以环己烷为带水剂及苯甲醛与甘油的摩尔比为2∶3的情况下,KHSO4为催化剂的缩合产物(1+2)收率较高,为96.8%;PTSA催化的缩合产物中,化合物1的比例最高(m(1)∶m(2)=48.6∶51.4)。室温下PTSA、PWA、KHSO4和FeCl3均可催化化合物2向化合物1的转化。在-20℃下,只有PTSA能催化化合物2向化合物1的转化。在-20℃,PTSA催化化合物2转化成化合物1a,并以晶体形式从苯(40%)-石油醚(60%)中析出。母液循环转化3次后,化合物1a的累计收率可达91.1%。     

铌酸催化的苯甲醛与甲醇缩合反应

采用铌酸为催化剂,探索了该催化剂对苯甲醛与甲醇缩合反应的影响.优化反应条件是,催化剂用量为反应物质的量的5mol%,甲醇10mL(兼作溶剂),回流状态下反应2h,反应的产率和转化率分别达到94%、98.0%.该催化剂同样适用于其他醛(酮)与甲醇的缩合反应,可得到34%～89%的产率.所述方法操作简单、产率高、选择性好而且对环境友好,反应结束后,催化剂很容易回收,并能有效重复使用.     

分子筛催化苯甲醛与醇缩合反应的研究

1　引言分子筛作为催化剂由于其特殊的酸性和择形性在精细有机合成中获得了广泛的应用[1],在缩醛化反应中也表现出了良好的催化性能,如Joshi[2]等用HY和HZSM5分子筛作催化剂,将苯甲醛与甲醇缩合,获得了83%的苯甲缩甲醛,并考察了不同种类的醛在HZSM5分子筛上的择形性。王存...     

硅钨酸催化合成苯甲醛1,2-丙二醇缩醛

以硅钨酸为催化剂,通过苯甲醛和1,2-丙二醇反应合成了苯甲醛1,2-丙二醇缩醛。实验结果表明,硅钨酸对缩醛反应具有较高的催化活性,反应的最佳条件为：苯甲醛150mmol,n(苯甲醛)：n(1,2-丙二醇)：1.0：1.5,催化剂0.7％(反应物料总质量),带水剂环己烷8mL,反应温度85℃～125℃,反应时间1．0h,收率达88．9％．     

改性活性炭负载三聚磷酸二氢铝催化合成苯甲醛乙二醇缩醛

采用硝酸改性活性炭后负载三聚磷二氢铝用于催化合成苯甲醛乙二醇缩醛,通过单因素实验考察醇醛摩尔比、催化剂用量及反应时间等因素对产品收率的影响,并采用正交实验获取较佳工艺条件。 结果表明,该催化反应中,当反应温度为110 ℃时,各因素对收率的影响顺序为:醇醛比>反应时间>带水剂加入量>催化剂用量。 优化反应条件为:苯甲醛0.2 mol,醇醛摩尔比2.5,反应时间75 min,催化剂加入量4%(占反应物总质量),带水剂加入量25 mL,苯甲醛乙二醇缩醛收率86.5%,催化剂经5次重复使用后收率仍大于86.0%。     

近临界水中苯甲醛与丙酮的Claisen-Schmidt缩合反应

在近临界水中进行有机合成为可持续化学合成提供了新的途径。对近临界水中苯甲醛与丙酮的Claisen-Schmidt缩合反应的研究表明,在没有外加任何催化剂的条件下,苯甲醛与丙酮可顺利地发生缩合反应,近临界水在其中兼作溶剂和催化剂,避免了碱催化剂的使用和随后繁杂的中和、分离步骤以及产生废弃盐等弊端。温度、反应时间和初始水量对反应的转化率和苯丁烯酮的产率有不同的影响。     

(S)-脯氨酸催化的对硝基苯甲醛和丙酮的Aldol缩合反应——推荐一个高年级本科生科研训练实验

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。     

甘油缩合制丙酮缩甘油中催化剂及反应机理研究进展

随着生物柴油产业的蓬勃发展,其主要副产物甘油的资源化利用已亟不可待.其中,将甘油与丙酮缩合生成丙酮缩甘油(2,2-二甲基-1,3-二氧戊环-4-甲醇,Solketal)是极具前景的研究方向,因为Solketal作为燃料添加剂不仅能显著增强燃油的黏度和低温性能,还能显著地减少一氧化碳、固体小颗粒及其他环境不友好物质的排放...     

FeCl3掺杂聚苯胺催化合成苯甲醛1，2-丙二醇缩醛

FeCl3掺杂聚苯胺催化合成苯甲醛1;2-丙二醇缩醛;缩醛;三氯化铁;聚苯胺;掺杂     

对甲苯磺酸催化下二乙酰苯与含有羟基的苯甲醛的Aldol缩合反应

以对甲苯磺酸(p-TsOH)作催化剂, 二乙酰苯与含有羟基的苯甲醛发生aldol缩合反应, 合成了3个1,3-双[3-(取代苯基)丙烯酰基]苯衍生物1～3, 3个1,4-双[3-(取代苯基)丙烯酰基]苯衍生物4～6和2个中间体7, 8, 中间体7, 8再与含有羟基的苯甲醛发生aldol反应合成了3个1-[3-(4-羟基苯基)丙烯酰基]-4-[3-(取代苯基)丙烯酰基]苯衍生物9～11, 反应均能在2～6 d内完成, 操作和后处理简便. 以上11个新化合物均未见报道, 其结构经1H NMR, IR, MS和HRMS加以确证.     

Novel,Green, Simple and Uncatalyzed Route for High Yield Preparation of Benzaldehyde Glycol Acetal

A simple approach for the condensation of benzaldehyde with ethylene glycol was adopted without employing any catalyst. The study reveals that factors including temperature, molar ratio of reactants, and the water removal significantly influence the conversion ratio of benzaldehyde. The results indicate that the use of optimal reaction conditions such as temperature and water removing exhibits more pronounced effects on the conversion ratio of benzaldehyde compared with the use of catalysts. In a word, a green and simple method for the condensation of aldehyde and menthandiol has been devised and investigated.     

CO_2和丙三醇直接合成碳酸甘油酯的新方法

报道了一种以CO_2和丙三醇为原料,Cs_2CO_3为碱,DMF为溶剂,bmimBF_4为增溶剂,直接合成碳酸甘油酯(GC)的新方法。在最优反应条件[丙三醇5 mmol,Cs_2CO_310 mmol,CH_2Cl_25 m L,bmimBF_41 m L,DMF 5 m L,P(CO_2)1 MPa,于100℃反应24 h]下,GC收率76%,其结构经1H NMR和ESI-MS确证。在最优条件下进行50倍放大实验,GC收率72%。     

Condensation of 2-methylindole with acetophenones: An unexpected formation of 2-arylanilines

Abstract

2-Methylindole condenses with acetophenones under acidic conditions to produce 2-arylanilines in moderate to good yields. The reaction proceeds well with a range of 3′- and 4′- substituted acetophenones (fluoro-, chloro-, bromo-, iodo-, methyl, methoxy), and select 2′- substituted ones (fluoro-, methoxy-). No products were obtained with nitro- substitution in any position.     

Synthesis of Vinylene-Linked Thiopyrylium-, Pyrylium-, and Pyridinium-Based Covalent Organic Frameworks by Acid-Catalyzed Aldol Condensation

The development of new vinylene-linked covalent organic frameworks (COFs) with special ionic structure and high stability is challenging. Herein, we report a facile, general method for constructing ionic vinylene-linked thiopyrylium-based COFs from 2,4,6-trimethylpyrylium tetrafluoroborate and other common reagents by means of acid-catalyzed Aldol condensation. Besides, pyrylium-, and pyridinium-based COFs also can be prepared from the same monomer under slightly different reaction conditions. The COFs exhibited uniform nanofibrous morphologies with excellent crystallinities, special ionic structures, well-defined nanochannels, and high specific surface areas.     

Knoevenagel Condensation between Benzaldehyde and Malononitrile Over Magnesium Phosphates

The Knoevenagel condensation between benzaldehyde and malonitrile over different magnesium phosphates was studied. The structure and chemical surface properties of each solid, which determine their catalytic activity, were found to depend on the synthetic procedure used. The results obtained were compared with their basicity measured by phenol adsorption and their dehydrogenation selectivity in the conversion of 2-hexanol.     

取代苯甲醛肟羧酸酯的合成及生物活性研究(Ⅱ)——α-烷硫基苯甲醛肟羧酸酯的合成及生物活性

肟醚及肟酯衍生物是一类具有优良的杀虫、杀菌、杀螨及除草活性的化合物，有关此类化合物的研究非常活跃［１，２］．本研究组对拟除虫菊酯与芳香肟衍生物进行研究，发现菊酸肟酯类化合物具有良好的抗烟草花叶病毒和杀虫活性［３］．本文在前期研究工作的基础上，将烷硫基...     

Synthesis of Cyclic Glycerol Ether Cyclodextrin Derivatives and Investigation of their Binding Properties with Drugs

Epichlorohydrin was reacted with cyclodextrins to form the non-cyclic and cyclic glycerol ethers of - and -cyclodextrin (abbreviated as glyc-CD). Cyclic substitution extends the cyclodextrin cavity in a way that is as rigid and non-polar as the cavity of the parent cyclodextrin. Derivatives with extended cavities should better accommodate large or odd shaped molecules. The binding of drugs to the new cyclodextrin derivatives was investigated, through degradation rate studies and solubilization studies, and compared to that of -cyclodextrin, -cyclodextrin and hydroxypropyl--cyclodextrin. The inclusion binding of small molecules such as acetazolamide, ethoxyzolamide and chlorambucil, in the glyc-CDs was either increased or decreased compared to the other cyclodextrins. However, larger molecules, such as indomethacin and hydrocortisone, always bound better to the glyc-CDs with up to 180% increase in the stability constant. The degradation rate within the cyclodextrin cavity was not affected by the above derivation.     

Investigation in the Area of Furan Acetal Compounds. 13. Synthesis and Structure of 1,3-Dioxacyclanes Based on Furfural and Glycerol

The optimum conditions were found for the condensation of glycerol with furfural. It was shown that the reaction of glycerol with furfural gives a mixture of the cis and trans isomers of five- and six-membered furan 1,3-dioxacyclanes. The cis- and trans-5-hydroxy-2-furyl-1,3-dioxanes were isolated by column chromatography, and their stereochemical structure was established by IR and NMR spectroscopy.