马来酸二丁酯的杂多酸催化合成及动力学研究

考察了无机酸（如硫酸、盐酸）和新型杂多酸（如磷钨酸、硅钨酸）为催化剂,催化合成马来酸二丁酯的反应。结果表明,对于两类催化剂,其酯收率相当;确定了杂多酸催化合成马来酸二丁酯的反应级数为二级;PW12和SiW12杂多酸催化剂的表观活化能分别为60.4和57.0kJ/mol。     

固体酸催化合成马来酸二丁酯

制备了固体酸催化剂Zr(SO4)2/SiO2,并用于合成马来酸二丁酯,考察了Zr(SO4)2负载量、焙烧温度、焙烧时间等催化剂制备条件对催化活性的影响。采用FTIR、XRD、TG等方法对催化剂进行了表征分析。通过正交实验设计优化了固体酸Zr(SO4)2/SiO2催化合成马来酸二丁酯的工艺条件。实验结果表明,Zr(SO4)2/SiO2是合成马来酸二丁酯的良好催化剂,适宜的催化剂制备条件为:硫酸锆负载量57%,焙烧温度400℃,焙烧时间2 h。适宜的催化合成反应条件为:酐醇物质的量比为1∶2.5,催化剂用量为马来酸酐质量的6%,带水剂甲苯8 mL,反应时间2.0 h。在此条件下马来酸二丁酯的酯化率为98.5%。     

杂多酸催化研究新进展

杂多酸催化剂泛指杂多酸及其盐 ,是一类由中心原子 (即杂原子 ,如 P、 Si等 )和配位原子 (即多原子 ,如 Mo、 W等 )通过氧原子桥联方式进行空间组合的多氧簇金属配合物 (polyoxometalate) ,作为催化材料广泛应用于均相与多相催化反应体系 .近年来 ,杂多酸在催化领域中受到越来越多关注 ,主要原因是 :1 .随着石油化工与精细化工的发展 ,催化材料的多功能性成为研究的新目标 .杂多酸是一种酸碱性与氧化还原性兼具的双功能型催化剂 ,对于新催化过程的研究具有重要意义 ;2 .随着分子“剪裁”技术的迅速兴起 ,新型催化材料层出不穷 .杂多酸的阴…     

超临界二氧化碳中马来酸锌催化合成环状碳酸酯

在超临界二氧化碳中, 利用马来酸锌催化二氧化碳与环氧化物反应合成环状碳酸酯. 单独使用马来酸锌作为催化剂时, 对二氧化碳与环氧丙烷反应的催化活性较低, 而在DBU、DMAP、三乙胺、吡啶、咪唑或4-氨基吡啶等有机碱的存在下, 反应活性较高, 产物的收率得到明显提高. 有机碱作用的强弱顺序为DBU>Et3N>咪唑>4-氨基吡啶>DMAP>吡啶. 在压力为8 MPa, 温度110 ℃, 反应时间48 h条件下, 马来酸锌与DBU组成的二元催化系统可以催化二氧化碳与环氧丙烷反应, 得到83.4%产率的碳酸丙烯酯. 该二元系统也能催化其它环氧化物高产率地转化为相应的环状碳酸酯.     

杂多酸催化剂研究进展

1杂多酸概述杂多酸（Heteropolyacid）,也称多金属氧簇（Polyoxometalate）,是一类由氧原子桥接金属原子形成的金属-氧簇化合物.杂多酸具有良好的催化性能,是高效的双功能催化剂,即有酸催化性能,又具有氧化还原催化性能.杂多酸结构稳定,可以用在均相或者非均相催化环境,     

MCM-41负载型过氧磷钨杂多酸季胺盐催化剂的制备和结构性能的考察

合成了以MCM-41为载体的过氧磷钨杂多酸季胺盐系列催化剂,并用XRD,FTIR,BET等方法测定了催化剂的体表结构.发现不同晶化时间合成的MCM-41具有不同的孔结构和比表面,负载过氧磷钨杂多酸季胺盐以后的催化剂对18醇催化氧化成18酸表现了不同的催化性能,与无载体的过氧磷钨杂多酸季胺盐催化剂相比显示了更高的活性和选择性.     

固体酸催化合成马来酸二辛酯

首次将铌酸用于催化合成马来酸二辛酯,在酐醇摩尔比1：3,回流反应1h,催化剂用量为5g/mol酐的条件下,转化率为99．3％,选择性为85．6％,催化剂不经处理,可循环使用多次,且不污染环境,相对于一些常见催化剂,具有明显的优点。     

微波协同离子液体催化合成马来酸二丁酯

以马来酸酐和正丁醇为原料,用微波协同离子液体[HSO3-pmim]+[HSO4]-催化合成了马来酸二丁酯。通过单因素实验和正交试验考察催化剂种类、催化剂用量、马来酸酐与正丁醇物质的量比、微波功率、微波时间对马来酸二丁酯产率的影响。实验结果表明,马来酸二丁酯最佳合成条件为:马来酸酐与正丁醇物质的量比1∶4,以离子液体[HSO3-pmim]+[HSO4]-为催化剂,其用量为2.0g,微波功率为600W,微波时间为15min,马来酸二丁酯产率可达到99.36%。在微波辐射下,催化剂离子液体[HSO3-pmim]+[HSO4]-重复使用7次后活性没有明显降低,马来酸二丁酯产率仍高于96%,表明该催化剂具有较好的反应活性和稳定性。与常规加热方式相比,微波加热提高了反应效率,缩短了反应时间。     

合成乳酸正丁酯的主要催化剂述评

综述聚氯乙烯—三氯化铁树脂、强酸性阳离子交换树脂、氨基磺酸、甲基磺酸、维生素C、稀土化合物、硅胶固载硫酸钛、硫酸铁铵、硫酸氢钠、磁性固体超强酸、酸改性高岭土、杂多酸(盐)等数种不同催化剂催化合成乳酸正丁酯的实验结果.结果表明,强酸型阳离子交换树脂、硫酸氢钠、磁性固体超强酸、硅胶固载硫酸钛、活性炭固载杂多酸五种催化剂催化合成乳酸正丁酯的酯收率较高,具有实际使用价值.     

混合金属氧化物固载杂多酸的制备及催化性能

杂多酸是一类含氧桥的多核无机高分子化合物,由于其独特的笼型结构而具有许多优异的性能,尤其是作为一种新型的多功能催化剂越来越受到人们的关注。因此,近年来人们一直致力于研究新型固载杂多酸催化剂。本文介绍了钛钨混合金属氧化物固载杂多酸催化剂HPA／TiO2-WO3的制备,及催化合成甲酸环己酯的方法,此法具有反应时间短、催化剂价廉易得、工艺简单、酯产率较高等优点。     

Synthesis of eudistomin C and E: improved preparation of the indole unit

An improved synthesis of the indole unit, a key intermediate for eudistomin C, was established utilizing Makosza's indole synthesis. A concise total synthesis of eudistomin E was achieved on the basis of the improved synthesis.     

Solid-phase synthesis of polyfunctional polylysine dendrons using aldehyde linkers

A straightforward method for the solid-phase synthesis of C-terminally modified polylysine dendrons has been developed by applying bisalkoxybenzaldehyde and trisalkoxybenzaldehyde linkers. The method has been used for the synthesis of polylysine dendrons with a variety of C-terminal ‘tail groups’ such as alkyl, propargyl, and dansyl to give dendrons in high crude purity. Furthermore, the method was successful for the synthesis of dendrons with multiple N-terminal pentapeptide groups together with C-terminal alkyl and propargyl tail groups. Finally, the method was shown to be well-suited for automated synthesis.     

Nucleosides and Nucleotides. Part 21. Synthesis of a Tridecanucleoside Dodecaphosphate Incorporating the Unnatural Base 2 (1 H)-Pyridone

The modified nucleoside Π_d (1) was used in the synthesis of the oligonucleotide d (TpTpΠpCpGpTpCpApApApApTpC). Diester methodology being unsatisfactory, the triester synthesis was investigated with the unnatural nucleoside. An improved method of nucleoside phosphorylation was developed for the synthesis of the fully-protected nucleotide 2e. This molecule could be cleanly and selectively deprotected, and allowed the efficient synthesis of the desired oligonucleotide.     

A Simple Synthesis of γ-Cyclohomocitral

A simple and efficient synthesis for γ-cyclohomocitral (10), a key and versatile intermediate for the synthesis of some furanosesquiterpenes, is described. The formal total synthesis of (±) Pallenscensone (2) was accomplished.     

An efficient ionic liquid supported divergent assembly of 3,6-branched glucosamine-containing pentasaccharide

We utilized the glycosyl acceptor tagging method with ionic liquid support for synthesis of the core segment of Clostridium botulinum C2 toxin ligand through a divergent synthetic strategy without chromatographic purification.The total yield was 57.1% and the reaction was completed in 10 h.The efficient ionic liquid supported glycosylation and purification procedure was applied for the synthesis of branched glucosamine-containing oligosaccharides for the first time,which expanded the scope of ionic liquid supported synthesis of biologically important oligosaccharides.     

Optimized Synthesis of Tetrakis(4-methoxyphenyl)porphin–Co(II)

Detailed kinetic investigation of Rothemund synthesis of porphyrins was conducted in different solvents. A one-pot synthesis of tetrakis(4-methoxyphenyl)porphin–Co(II) from pyrrole, anisic aldehyde, and cobalt acetate was developed that gave 35% isolated yield. Chlorobenzene was found to be the best solvent for the reaction. The synthesis can be done with either propionic or chloroacetic acid as catalyst with about the same yield. Cobalt prevents the synthesis of the porphyrin, so it has to be added in the reaction mixture only after the synthesis of the free porphyrin is finished. Optimum time is 2–2.5 h at a temperature of 130°C. Lower temperatures reduce the yield. Potentially, these dependencies can be applied to synthesis of other analogous porphyrins.     

Stereoselective syntheses of γ-alkyl (aryl)-α,β-dihydroxy-γ-butyrolactones and naturally occurring lipid guggultetrol

γ-Oxo-butyramides derived from tartaric acid serve as excellent precursors for the synthesis of γ-alkyl (aryl)-α,β-dihydroxy-γ-butyrolactones and for the synthesis of tetrols containing three contiguous stereogenic centres. The methodology presented here is general for the synthesis of γ-alkyl (aryl)-α,β-dihydroxy-γ-butyrolactones. Utility of the chiral building block was demonstrated by the synthesis of naturally occurring lipid guggultetrol.     

Nickel-catalyzed esterification of mandelic acids with alcohols

Mandelates and their derivatives are widely used in organic synthesis, drug discovery, biodegradable polymers and other related fields. Therefore, the effective and simple synthesis of these compounds has attracted much attention. In this paper, a nickel(II)-catalyzed esterification of mandelic acids with different alcohols was realized for the synthesis of mandelic acid esters. This transformation was conducted under mild reaction conditions with yields up to 95%, and was successfully utilized in the gram-scale synthesis of medicine cyclandelate.     

Stereoselective Synthesis of Piperamide Alkaloids by Modified Ramberg-Bcklund Reaction

A convenient and rapid approach for the synthesis of piperamide alkaloids la ~ h by the recently developed one-flask Ramberg-Backlund reaction was described. The synthesis of 1e was reported for the first time.     

Wavelength dependence of mycosporine-like amino acid synthesis in Gyrodinium dorsum

The synthesis or accumulation of mycosporine-like amino acids (MAAs) is an important UV tolerance mechanism in aquatic organisms. To investigate the wavelength dependence of MAA synthesis in the marine dinoflagellate Gyrodinium dorsum, the organism was exposed to polychromatic radiation (PAR and UV) from a solar simulator for up to 72 h. Different irradiance spectra were produced by inserting various cut-off filters between lamp and samples. A polychromatic action spectrum for the synthesis of MAA synthesis was constructed. PAR and long wavelength UV-A radiation showed almost no effect while the most effective wavelength range was around 310 nm. Shorter wavelengths where less effective in the induction of MAA synthesis. Wavelengths below 300 nm damaged the organisms severely as indicated by a decrease in chlorophyll a absorption.