微波辐射用于聚合反应的研究进展

微波辐射在高分子化学研究领域中的应用越来越广泛 ,效果也十分明显 ,与常规加热方式相比 ,微波辐射具有缩短反应时间 ,提高反应产率 ,节省能源损耗 ,制得产物性能好等优点。近年来 ,微波辐射在聚合反应中的应用也越来越多。因此本文对微波辐射在高分子聚合反应中的应用研究进行了综述。     

含氧膦结构的可溶性感光聚酰亚胺合成与表征

聚酰亚胺(PI)是一类综合性能优异的功能性材料,广泛应用于航天、航空及电子工业等领域[1].感光聚酰亚胺可以采用光刻工艺,大大简化了其应用加工程序[2,3],因而备受人们所青睐.含查尔酮结构的聚合物对UV辐射敏感度高和化学稳定性好,最近被广泛的研究和应用[4～7].主链含查尔酮结     

微波辐射在合成沙利度胺中的应用

以邻苯二甲酸醉和尿素为原料,应用微波辐射加热技术,共经过四步合成目标产物沙利度胺的方法,且产物不需要经过多次纯化.考察了辐射功率、辐射时间、原料配比、溶剂用量等对收率的影响.与常规加热方法合成沙利度胺比较,微波辅助合成在提高产率的同时大大缩短了反应时间,且具有操作简单、环境污染小、产品质量好等优点.     

微波辐射下双(2-苯并咪唑基)丙烷的合成与结构表征

与传统加热相比较,微波辐射促进的有机合成反应具有加热时间短、节能、产率高、不使用或少使用溶剂而对环境友好和节约成本等优点[1]。苯并咪唑类化合物具有广泛的生物活性而被应用到仿生有机合成、遗传学染色体研究及单层膜合成与形态研究的领域[2～4]。苯并咪唑类化合物的传统合成方法是:在HC1、多聚磷酸(PPA)、H3BO3等酸性催化剂使用下加热回流有机酸与邻苯二胺的混合物,然而反应通常需要较高的压力、温度或较长的时间,副反应多[5]。本研究在微波辐射下,以戊二酸和邻苯二胺为原料、PPA为催化剂合成了双(2-苯并咪唑基)丙烷,用正交试…     

磷酸钙纳米结构材料的微波辅助液相合成

微波加热作为一种新兴热源具有加热速率快、制备时间短、节能等优点,已经被广泛应用于合成包括磷酸钙在内的多种无机纳米材料.磷酸钙作为典型的生物材料,其制备新方法的探索、结构/尺寸/形貌调控、性能研究和应用探索是生物材料领域的一个重要研究方向.本文阐述了微波辅助合成法用于制备纳米材料的优势,并综述了微波辅助液相快速合成磷酸钙纳米结构材料的进展.采用微波液相合成技术,可以制备出包括颗粒、一维、二维和三维结构在内的多种磷酸钙纳米结构材料,同时还可以通过功能性组分的掺杂/复合对磷酸钙纳米材料进行功能化.预期未来微波液相合成法在包括磷酸钙在内的多种无机纳米材料的合成领域将得到快速发展和广泛应用;另外,微波液相合成的磷酸钙纳米结构材料在药物递送和控释、蛋白吸附、金属离子吸附、生物成像及骨缺损修复等众多领域具有良好的应用前景.     

植物纤维微波辐射预处理的研究进展

综述了微波辐射预处理技术在植物纤维发酵、纸浆生产、木材加工三个化学加工中的应用研究进展。结果表明,微波辐射预处理能有效地提高植物纤维的化学反应和加工性能,而且预处理作用深度大,具有缩短反应时间,提高生产效率,降低生产能耗等优点。并且指出了微波辐射预处理植物纤维的不足:应用范围有限,其工业化研究处于探索阶段;升温快,反应过程不易控制。最后提出未来研究的重点:微波辐射预处理植物纤维加速反应机理、温度的控制和检测方法等方面。     

苯乙炔基封端聚酰亚胺材料研究进展

在过去二十年中，芳香族聚酰亚胺材料得到越来越广泛的应用，其中苯乙炔基封端的聚酰亚胺材料因其优异的性能成为目前耐高温聚合物材料研究的热点。本文综述了苯乙炔基封端聚酰亚胺材料的研究现状与发展趋势，着重对材料的化学结构设计与制备方法、以及化学结构与性能之间的关系进行介绍。     

微波技术在生物可降解聚合物合成中的研究进展

阐述了微波合成技术及微波化学仪器的发展历史,综述了微波辐射技术在生物可降解聚合物合成中的特点和优势,并针对其在直接缩聚法、开环聚合法以及共聚合成可生物降解聚合物中的应用和研究成果做了重点介绍。研究发现微波辐射技术具有大大降低聚合反应的时间和能耗,提高反应聚合速率、收率,且具有一定选择性的特性。而作为一种新型高效的加热方式,微波辐射技术为生物可降解聚合物合成甚至更多高分子材料的合成提供了新的思路。     

光敏聚酰亚胺光刻胶研究进展

近年来,光敏聚酰亚胺(PSPI)在先进封装、微机电系统和有机发光二极管(OLED)显示等新兴领域的需求牵引下得到了快速发展。在基础研究、应用研究以及产业化方面,PSPI的进展都引起了广泛关注。光敏聚酰亚胺作为一种实用的可自图案化薄膜材料显示出越来越突出的重要性。本文综述了近年来正性、负性光敏聚酰亚胺的结构设计、光化学反应及其感光性能等方面的研究进展,简要介绍了在集成电路、微机电系统以及OLED显示等方面的应用需求,最后对光敏聚酰亚胺在研究和应用中存在的问题及其前景进行了展望。     

高分子材料的微波辅助合成研究进展

微波加热以其省时、高效、清洁环保的显著优势而使微波辅助合成成为一种广受欢迎的合成技术。高分子材料的传统合成反应时间长、耗能大。将微波辐射应用于高分子材料的合成可缩短反应时间、降低反应能耗,已成为有机合成领域的研究热点。本文简要综述了微波辅助合成技术在工程材料高分子聚酰胺、聚酰亚胺、聚丙烯酸苄基酯以及在医用功能高分子、吸附功能高分子、导电功能高分子和光学功能高分子合成中的研究进展,并展望了微波辅助合成在高分子材料合成中的发展前景。     

Kinetic studies of the copper-catalyzed cross-coupling of 1-phenyltetrazole-5-thiol and iodobenzene

Kinetics of the copper-catalyzed cross-coupling of 1-phenyltetrazole-5-thiol and iodobenzene under thermal and dielectric heating has been studied; the kinetic parameters of the reaction have been calculated. Microwave irradiation has not influenced significantly the reaction molecular mechanism; the process acceleration can be due to macrokinetic effects.     

Cross-metathesis assisted by microwave irradiation

Microwave irradiation effectively accelerates cross-coupling metathesis reactions between deactivated olefins. Reactions have been carried out with the phosphine-free Hoveyda-Grubbs catalyst and the "second generation Grubbs' catalyst." While there have been reports that a "microwave effect" is observed in various transformations, the accelerations we observe are due to the efficient and rapid heating and increased pressure in the microwave apparatus.     

The synthesis of indanones related to combretastatin A-4 via microwave-assisted Nazarov cyclization of chalcones

A fast and efficient microwave-assisted synthesis of combretastatin A-4-like indanones has been developed. Microwave irradiation provides a useful alternative to traditional heating techniques to promote the TFA-catalyzed Nazarov cyclization of chalcones.     

Microwave-assisted reactions in heterocyclic compounds with applications in medicinal and supramolecular chemistry

Microwave irradiation has been successfully applied in organic chemistry. Spectacular accelerations, higher yields under milder reaction conditions and higher product purities have all been reported. Indeed, a number of authors have described success in reactions that do not occur under conventional heating and modifications in selectivity (chemo-, regio- and stereoselectivity) have even been reported. Recent advances in microwave-assisted combinatorial chemistry include high-speed solid-phase and polymer-supported organic synthesis, rapid parallel synthesis of compound libraries, and library generation by automated sequential microwave irradiation. In addition, new instrumentation for high-throughput microwave-assisted synthesis continues to be developed at a steady pace. The impressive speed combined with the unmatched control over reaction parameters justifies the growing interest in this application of microwave heating. In this review we highlight our recent advances in this area, with a particular emphasis on cycloaddition reactions of heterocyclic compounds both with and without supports, applications in supramolecular chemistry and the reproducibility and scalability of organic reactions involving the use of microwave irradiation techniques.     

Microwaves in organic synthesis. Thermal and non-thermal microwave effects

Microwave irradiation has been successfully applied in organic chemistry. Spectacular accelerations, higher yields under milder reaction conditions and higher product purities have all been reported. Indeed, a number of authors have described success in reactions that do not occur by conventional heating and even modifications of selectivity (chemo-, regio- and stereoselectivity). The effect of microwave irradiation in organic synthesis is a combination of thermal effects, arising from the heating rate, superheating or "hot spots" and the selective absorption of radiation by polar substances. Such phenomena are not usually accessible by classical heating and the existence of non-thermal effects of highly polarizing radiation--the "specific microwave effect"--is still a controversial topic. An overview of the thermal effects and the current state of non-thermal microwave effects is presented in this critical review along with a view on how these phenomena can be effectively used in organic synthesis.     

Hot or not—the influence of elevated temperature and microwave irradiation on the solid phase synthesis of an affibody

Despite the advances of solid phase peptide synthesis (SPPS) the synthesis of long peptides is still challenging. Microwave irradiation and conventional heating are considered to improve the efficiency of SPPS. It has been shown that conventional heating and heating by microwave irradiation improves the efficiency of solid phase synthesis of peptides that are prone to aggregation as compared to the synthesis at room temperature. In this Letter, the influence of elevated temperature and microwave irradiation on the homogeneity of the synthesis product of a 58-mer peptide affibody has been compared. A detailed analysis by high resolution HPLC and LC-MS mass spectrometry using a high-mass resolution Orbitrap Exactive mass spectrometer was performed. This study revealed that neither thermal heating nor microwave heating improves the yield and purity of the crude product as compared to the synthesis at room temperature. In contrast, the formation of undesirable side products rather increased by microwave irradiation. These results indicate that neither heating nor microwave enhancement of solid phase synthesis does allow a significant improvement of peptide sequences with a low aggregation potential.     

微波技术在催化剂制备中的应用

微波作为一种独特的加热手段在化学领域已得到广泛应用。本文综述了微波技术在催化剂的合成、活性组分的负载等方面的研究应用,重点探讨了在分子筛催化剂的合成中微波技术所表现出的优越性,对微波合成催化剂的作用机理及影响因素作了评述,并展望了微波技术在催化领域的发展前景。     

Observations on the use of microwave irradiation in azaheterocycle synthesis

A comparison of conventional heating and microwave irradiation in the synthesis of azaheterocycles is discussed. Microwave irradiation was found to increase the yields of the desired products, shorten the reaction times, and extended this chemistry to recalcitrant amide substrates and weak nucleophiles.     

Microwave Effects Due to Anionic or Cationic Initiators in Emulsion Polymerization Reactions

Summary: Emulsion polymerization reactions were performed under microwave irradiation and conventional heating using anionic or cationic initiators and surfactants. Microwave irradiation promoted higher reaction rates for both initiators and surfactants, in comparison with the conventional heating. The effect of high power microwave irradiation was studied using a method of cycles of heating and cooling, where rapid polymerization reactions were obtained. In the reactions with anionic initiator and surfactant, a decrease in the particle diameters was observed with microwave heating, and even smaller particles were obtained using high power microwave irradiation. Moreover, the decrease in the particle size was acompanied by an increase in the polymer molecular weight. On the other hand, these effects were not observed for reactions with cationic initiator and surfactant.