三溴化聚乙烯吡咯烷酮高效催化醇和酚的乙酰化反应(英文)

An efficient and versatile procedure for the acetylation of alcohols and phenols using acetic anhydride in the presence of a catalytic amount of polyvinylpolypyrrolidoniume tribromide has been successfully developed.Primary,secondary,and tertiary alcohols,as well as a selection of the phenolic compounds,have been successfully acetylated according to this procedure,with good to high yields being achieved over short reaction times.     

Silica Chloride as a Mild and Efficient Reagent for Acetylation of Alcohols

A variety of alcohols underwent acetylation with acetic anhydride in the presence of silica chloride. All reactions were performed at room temperature and under completely heterogeneous conditions in good to high yields.

     

无溶剂条件下ZnBr2催化醇与苯甲酸酐的酰化反应

以溴化锌为催化剂,在无溶剂条件下实现了醇与苯甲酸酐的酰化反应,部分产物经NMR和IR表征。     

Rapid and Efficient Method for Acetylation of Alcohols and Phenols with Acetic Anhydride Catalyzed by Silica Sulfate

A rapid and efficient method is described for acetylation of a series of alcohols and phenols with acetic anhydride catalyzed by silica sulfate solid acid at room temperature or at refluxing temperature in excellent yield.     

PPA-SiO_2 as a Heterogeneous Catalyst for Efficient Synthesis of 2-Substituted-1,2,3,4-tetrahydro-4-quinazolinones under Solvent-free Conditions

Silica‐supported polyphosphoric acid (PPA‐SiO₂) catalyzed efficiently the reaction of anthranilamide with aryl aldehydes or ketones under solvent‐free conditions to afford the corresponding 1,2,3,4‐tetrahydro‐4‐quinazolinone derivatives. This work consistently has the advantages of excellent yields, short reaction time, simple experimental and work‐up procedures. The heterogeneous catalyst could be recovered and recycled for several times without any loss of its activity.     

盐酸三甲胺三氧化铬／硅胶对醇类化合物的氧化研究

报道了盐酸三甲胺三氧化铬／硅胶对醇类化合物的氧化反应。盐酸三甲胺三氧化铬／硅胶可在多种介质中氧化伯醇和仲醇成为相应的醛或酮，反应条件温和、操作简单、收率高。     

Oxidation of Alcohols with 4-Aminopyridinium Chlorochromate Supported on Silica Gel

Summary. 4-Aminopyridinium chlorochromate supported on silica gel was found to be an efficient reagent for the oxidation of primary and secondary alcohols to the corresponding carbonyl compounds.     

Silica Sulfate,an Efficient Catalyst for the Trimethylsilylation of Alcohols

An easy method for the preparation of trimethylsilyl ethers from alcohols and 1,1,1,3,3,3‐hexamethyl‐disilazane (HMDS) using silica sulfate as a catalyst under mild conditions in excellent yields is described.     

Silica Supported Methanesulfonic Acid as an Efficient and Reusable Heterogeneous Catalyst for the Synthesis of Amidoalkyl Naphthols

A green protocol for the preparation of amidoalkyl naphthols from three‐component one‐pot condensation of 2‐naphthol, aldehydes, amides or urea in the presence of silica supported methanesulfonic acid under thermal solvent‐free conditions has been described. The catalyst is stable, efficient, easily prepared, and reusable. The remarkable features of this methodology are short reaction time, excellent yields, simple experimental and work‐up procedures.     

An Efficient Method of Solid‐State Synthesis of Diazenecarboxamide Azo Compounds Using Active Manganese Dioxide Supported on Acidic Silica Gel

An efficient solid‐state method to oxidize aryl‐substituted semicarbazides into their corresponding N‐aryl‐2‐phenyldiazenecarboxamides with active manganese dioxide (AMD) supported on acidic silica gel is described. With this method, eleven diazenecarboxamides have been synthesized in high yields.     

Al(HSO4)3 as an Efficient Catalyst for the Acetylation of Alcohols in Solution and Under Solvent Free Conditions

Summary. Alcohols are acetylated in a mild, clean, and efficient reaction with acetic anhydride in the presence of a catalytic amount of Al(HSO₄)₃ in solution and under solvent free conditions. All reactions were performed at room temperature in good to high yields.     

Silica-bonded S-Sulfonic Acid: A Recyclable Catalyst for the Synthesis of Trisubstituted Imidazoles under Solvent-free Conditions

Trisubstituted imidazoles have been synthesized in high yields in the presence of silica‐bonded S‐sulfonic acid as a catalyst. The reaction was carried out at 130°C under solvent‐free conditions. The reaction work‐up is simple and the catalyst is easily separated from the products by filtration.     

硅胶负载钯: 一种新型有效而可循环的Heck反应的催化剂

本文报道了一种新型硅胶负载钯催化剂在Heck 反应中的应用。在硅胶负载钯催化剂,碳酸钾为碱,DMF为溶剂的反应条件下（无膦和无游离胺的存在）,碘代芳烃、溴代芳烃和活泼的氯代芳烃与烯烃发生偶联反应生成高产率相应的偶联产物。而且硅胶负载的钯催化剂经简单处理,可循环使用6次不降低活性。     

Preconcentration of Uranium in Seawater with Heterocyclic Azo Dyes Supported on Silica Gel

Abstract

The chelating adsorbents, heterocyclic azo dyes supported on silica gel, were prepared and their adsorption behaviors of metal ions were investigated. The 1-(2-pyridylazo)-2-naphthol(PAN)-SG and 2-(2-thiazolylazo)-p-cresol(TAC)-SG show greater affinity for UO₂(II) and ZrO(II), compared with the other metal ions like Cu, Cd, Fe and alkaline earths. Trace uranyl can be quantitatively retained on the column of the gels at neutral pH region and flow-rate 3–4 ml/min. The uranyl retained is easily eluted from the column bed with a mixture of acetone and nitric acid(9:1 v/v) and determined by spectrophotometry using Arsenazo-III. Matrix components in seawater do not interfere and the spiked recovery of uranyl in artificial seawater was found to be average 98.6 %, with the relative standard deviation of 1.08 %. Both gels were applied to the determination of uranium in seawater with satisfactory results.     

Brönsted Acidic Ionic Liquid as an Efficient Catalyst for Acetylation of Alcohols and Phenols

A novel Brönsted acidic room temperature ionic liquid (1‐H‐3‐methyl‐imidazolium bisulfate) is found to catalyze efficiently the acetylation of a wide rang of alcohols as well as phenols with acetic anhydride in good to excellent yields at 50°C under solvent‐free conditions. Products are easily isolated by extraction with ether and the protocol is mild and green, compared to the existing method based on toxic solvents.     

Synthesis of Maleic Anhydride by Oxidizing Furfural over Phosphorusmolybdenumic Acid Supported on Silica Gel

采用浸渍法制备负载型磷钼杂多酸催化剂,分析了催化剂的比表面积、分散性、结构特征、稳定性以及再生温度等性质.通过固定床微反应器考察杂多酸催化剂催化氧化糠醛生成顺丁烯二酸酐的催化性能.研究了焙烧温度、负载量对催化剂性能的影响,以及反应温度对顺丁烯二酸酐收率的影响.结果表明：通过浸渍制备的杂多酸催化剂具有杂多酸催化剂的Keggin结构,具有较好的稳定性和酸性;活性组分能较好的分布于载体SiO2上;催化剂的再生温度和活化温度均为400℃;在钼磷原子比为0.85,负载量为48.6%时催化性能较好,催化剂的表面酸量为0.646 mmol/g;反应温度控制在365℃附近时,顺丁烯二酸酐收率可达到57.2%,选择性为62.7%.     

凝胶渗透色谱用大孔硅胶的制备

采用ＮａＣｌ、ＬｉＣｌ～ＫＮＯ３３组分盐，通过一次焙烧扩孔，制备了孔径４×１０２～１×１０３ｎｍ的大孔硅胶，其孔容可达０．８ｍＬ／ｇ，孔度为０．６５以上。实验结果表明，可用于ＧＰＣ分离相对分子质量为１．５×１０７以下的聚丙烯酰胺。     

Silica Gel,an Effective Catalyst for the Reaction of Electron-Deficient Nitro-Olefins with Nitrogen Heterocycles

The reaction of electron-deficient olefins with nitrogen heterocycles such as pyrrole and indole was examined in the presence of silica gel at room temperature under stirring at solvent-free conditions. It was found that silica gel is an effective catalyst for this conjugate addition. This work resulted in the formation of monosubstituted pyrroles selectively as a major product except in a few cases where disubstituted pyrroles were also formed as side products. Thus, a simple, rapid, efficient, environmentally benign, and solvent-free method was established.     

Highly Efficient Etherification and Oxidation of Aromatic Alcohols Using Supported and Unsupported Phosphorus Pentoxide as a Heterogeneous Reagent

A highly efficient procedure for etherification and oxidation of aromatic alcohol is described using unsupported and supported P₂O₅ on alumina and/or silica gel. The silica gel and alumina proved to be the most suitable support among the supports examined in our experiments. It was illustrated that the etherification and oxidative performance in reactions depend largely upon variables including reaction temperature, the nature of the P₂O₅ used (supported or unsupported P₂O₅), and whether solvent-free conditions are applied. It was shown that P₂O₅ not only can convert the aromatic alcohols into corresponding ethers and/or aldehyde and ketone but also can convert aromatic ethers into aldehyde or ketone via oxidative cleavage. Finally, quantum mechanical calculations were performed to rationalized these events, and it was indicated that aldehyde and ketone are more favorable products on the basis of the heat of formation (ΔH_f).

硅胶负载磷钼杂多酸催化氧化糠醛制顺丁烯二酸酐

采用浸渍法制备负载型磷钼杂多酸催化剂,分析了催化剂的比表面积、分散性、结构特征、稳定性以及再生温度等性质.通过固定床微反应器考察杂多酸催化剂催化氧化糠醛生成顺丁烯二酸酐的催化性能.研究了焙烧温度、负载量对催化剂性能的影响,以及反应温度对顺丁烯二酸酐收率的影响.结果表明:通过浸渍制备的杂多酸催化剂具有杂多酸催化剂的Keggin结构,具有较好的稳定性和酸性;活性组分能较好的分布于载体SiO2上;催化剂的再生温度和活化温度均为400℃;在钼磷原子比为0.85,负载量为48.6%时催化性能较好,催化剂的表面酸量为0.646 mmol/g;反应温度控制在365℃附近时,顺丁烯二酸酐收率可达到57.2%,选择性为62.7%.