微波有机化学的应用与研究进展分析

随着科技的进步和文明的发展,当代社会对化工和化学相关领域提出了"绿色化学"的概念,要求既要经济发展,也要保护环境。随着微波技术在化学领域中的广泛应用,在化学反应中,尤其是有机化学的反应中,传统的加热手段所带来的时间冗长、设备要求太高、操作过程复杂、反应收率不高等问题,都得到了有效的解决。介绍了微波技术的原理,并举例说明了微波技术在有机化学中的应用与研究进展。     

绿色化学理念在有机化学实验教学的应用实践探究

为了探究绿色化学理念在有机化学教学中的应用,从绿色化学理念的价值、绿色化学理念在实验室建立、实验内容设计、绿色实验技术等三个方面的应用阐述。     

微波有机合成及在混凝土减水剂制备中的应用研究进展

微波辐射作为反应活化的新型能源,已成为有机化学中普遍应用的先进技术。本文从过热、热点和选择性加热以及高极化场下的非热效应4方面阐述微波有机合成机理,结合国内外应用案例进行理论验证。重点从反应动力学角度分析了微波辐射对提高混凝土减水剂品质上的作用效果,总结了近几年微波辅助合成减水剂的研究进展,旨在推动微波技术在水泥混凝土外加剂领域中的实际应用。最后,提出微波辐射通过在电磁场作用下极性分子的快速振动实现,其热效应对体系起深层加热作用,非热效应改变反应动力学,但对作用的反应体系具有"选择性",应着重分析。微波辅助合成减水剂具有显著优势,可增大反应速率常数且存在非热效应,应加深研究及进一步推广。     

Recent advances in microwave initiated synthesis of nanocarbon materials

This Feature Article focuses on the recent advances in synthesis of nanostructured carbon materials using microwave irradiation as the heating source. Although the microwave approach to chemical synthesis is relatively mature in organic synthesis, it is still in the early stage for nanomaterials synthesis, especially nanocarbons. Due to the energy efficient nature of microwave heating, there is a great opportunity to apply microwave irradiation to nanocarbon production, which normally requires high temperature, high vacuum or inert gas protections. Using microwave irradiation will give a green feature to the nanocarbon synthesis, since it offers high efficiency heating and fast carbonization. With our recent discovery, multi-walled carbon nanotubes can be synthesized through the microwave process even in air. Background about nanocarbons and microwave chemistry are introduced, the application of microwaves in synthesis of different types of nanocarbons is discussed and finally, the perspectives in the future research directions of microwave assisted nanocarbon synthesis are deliberated as well.     

微波在酯化和水解反应中的应用

介绍了微波加热的基本原理和特点,回顾了微波化学反应器的研究进展及微波在酯化和水解反应中的应用研究现状,说明微波对酯化和水解反应有很大的促进作用。指出了今后研究的重点。     

微波促进有机反应原理及微波有机合成仪

论述了微波促进有机反应的原理和微波加热的特点.对目前使用的家用微波炉和专用微波有机合成仪的性能进行了评价.指出微波促进有机反应需要解决的问题及我国应加强对该领域的研究.     

微波加热用透波材料的研究进展

微波加热技术因其绿色环保、体积加热、选择性加热等优势,已被广泛应用于化工强化、金属冶炼、陶瓷烧结、食品加工等众多领域,但微波在反应器内普遍存在透波效果差、微波利用率低等问题。随着微波加热技术的不断发展,微波加热设备中透波材料的选用越来越受到大家的关注。本文主要针对透波材料在微波加热领域中的应用现状进行综述,对透波材料的种类进行简要介绍,分别从微波加热用容器和保温材料两方面进行论述。详细介绍了氧化物、氮化物、硅酸盐、磷酸盐等高温透波材料及聚四氟乙烯、玻纤增强树脂基、环氧树脂等中、低温透波材料的研究进展,并具体论述了目前微波加热常用纤维棉、纤维毯和纤维板等各种陶瓷纤维制品的介电特性和透波性能,最后指出了目前微波加热用透波材料普遍存在的问题,并对透波材料的应用和发展作出了展望。     

Microwave‐assisted dyeing of poly(butylene terephthalate) fabrics with disperse dyes

In this study, conventional heating and microwave dielectric heating in the exhaust dyeing of poly(butylene terephtalate) fabrics with disperse dyes were studied in order to determine whether microwave heating could be used to increase the dyeability of poly(butylene terephtalate) fibre in shorter processing times and enable dyeings of adequate wet fastness to be obtained. Accordingly, the samples of 100% poly(butylene terephtalate) single jersey knitted fabric were dyed with CI Disperse Yellow 160 and CI Disperse Yellow 42, CI Disperse Red 177 and CI Disperse Red 91, CI Disperse Blue 79:1 and CI Disperse Blue 54 at 98 °C with or without microwave dielectric heating. The colouristic properties, colour fastnesses and the tensile properties of the dyed fabrics were investigated and compared with each other. Microwave dielectric heating is regarded as a tool for ‘green chemistry’ and provides many advantages over conventional heating without any deterioration in the properties of the dyed materials. Microwave heat dyeing enhances the exhaustion and the fixation of dye, and good colour fastnesses and repeatability in dyeings are achieved in short heating times of the dyebath.     

微波辐射合成苯甲酸和苯甲醇的研究

采用微波密闭合成反应技术,对Cannizzaro反应进行了研究,研究了碱(NaOH)的质量分数、微波功率、辐射时间、反应温度对该反应的影响,通过测定苯甲酸熔点、苯甲醇的折光率检测产品纯度。结果表明:在微波辐射条件下,该反应速度快,比传统合成方法缩短反应时间数十倍,产率最高达85%,同常规方法相比有不同程度的提高。     

微波技术在分析化学中的应用进展

介绍了微波加热的机理和特点,综述了微波技术在分析化学中的应用,展望了微波技术的前景,提出了微波技术在分析化学中的发展方向和建议。     

微波技术用于热解的研究进展

微波加热作为一种独特的加热方式用于有机质的热解具有明显的优越性.综述了国内外有机质微波热解的研究应用,并通过分析物料特性,运行条件和是否添加微波吸收剂等因素对热解过程和产物的影响,对微波热解进行了阐述.展望了微波热解的应用前景,提出了需进一步研究和解决的问题.     

无溶剂条件下微波辅助合成硫氰酸酯类化合物

芳基硫氰酸酯是重要的有机合成中间体,得到越来越广泛的应用。文章研究了无溶剂条件下微波辅助合成的方法,用此方法合成了一系列的芳基硫氰酸酯。反应在几分钟内就能完成,并且收率大多在80%以上。该方法操作简单,反应时间短,产率高,环境友好,符合绿色化学的发展要求。     

浅谈以绿色化学新理念指导基础化学实验教学

介绍了绿色化学的内涵及其原则,阐明了在农科院校实施绿色化学的重要意义。探讨了在基础化学实验教学中实施绿色化学教育的几项措施。通过教育提高认识,树立绿色化学的新理念,开展微型、半微型化学实验,组联实验,使用微波、超声波等现代化的实验仪器,利用多媒体技术等多种手段,来达到绿色化学教学的目的。化学教育工作者应肩负起义不容辞的责任。     

绿色化学理念在化工专业有机化学实验教学中的渗透

介绍了绿色化学的内涵和原则,阐明了将绿色化学思想渗透到有机化学实验教学的重要性,探讨了在有机化学实验教学中实施绿色化学教育的几项措施,旨在培养具有绿色环保意识的应用型化工人才。     

绿色有机电致发光材料C545T合成工艺研究

研究了绿色有机电致发光材料C545T的合成工艺。以价格较便宜的1-溴-3-甲基-2-丁烯代替1-氯-3-甲基-2-丁烯,降低了原料价格,提高了产品收率;其次,中间体2-苯并噻唑乙酸乙酯的合成采用微波法代替传统的加热反应法,缩短了反应时间,提高了产品收率;另外,最后一步的Knovenagel反应采用有机碱哌啶作催化剂,也缩短了反应时间,提高了产品收率。该合成工艺生产周期短,反应条件温和,纯化过程简单,合成成本低,六步合成总收率达8.2%,产品纯度达99.9%。     

Microwave-assisted nonaqueous sol-gel deposition of different spinel ferrites and barium titanate perovskite thin films

Rapid and selective heating of solvents by microwave irradiation coupled to nonaqueous sol-gel chemistry makes it possible to simultaneously synthesize metal oxide nanoparticles within minutes and deposit them on substrates. The simple immersion of substrates, such as glass slides, in the reaction solution results after microwave heating in the deposition of homogeneous porous thin films whose thickness can be adjusted through the precursor concentration. Here we use such a microwave-assisted nonaqueous sol-gel process for the formation of various spinel ferrite MFe2O4 (M = Fe, Co, Mn, Ni) and BaTiO3 nanoparticles and their deposition as thin films. The approach offers high flexibility with respect to controlling the crystal size by adjusting the reaction time and/or temperature. Based on the example of CoFe2O4 nanoparticles, we show how the crystal size can carefully be tuned from 4 to 8 nm, resulting in a continuous change of the magnetic properties.     

绿色化学在焦油加工过程中的应用研究

考察了超临界技术、微波技术等绿色化学技术在煤焦油分离和深加工过程中的应用情况,利用超临界CO2对焦油进行分离可以获得与常规分离相类似的结果,分离过程高效、低耗。讨论了温度和压力对分离过程的影响。认为清洁、高效的绿色化学技术是有机化学、化工的发展方向,在煤焦油化学领域开展固体酸催化剂、离子型液体、超临界流体技术的研究对拓展研究方向具有重要意义。     

Controlled Microwave Heating and Melting of Gels

Controlled microwave heating and melting of silica, alumina, and aluminosilicate gels were achieved in a 600-W domestic-type oven. The microwave absorption mechanism of these gels is not yet clear. However, parameters were defined whereby rapid heating (including melting) is achieved for these gels. Empirical results indicate that the heating behavior is dependent on the chemistry, structure, and mass of the gel.     

An Efficient Eco-Friendly Synthesis of Pyran Annulated Heterocyclic Systems under Conventional Heating and Microwave Irradiation in Solvent-Free Conditions

1,4-Diazabicyclo[2.2.2]octane (DABCO) has been used as an efficient and reusable solid base catalyst for the rapid and green synthesis of pyran annulated heterocyclic ring systems by the condensation reaction of various activated CH-acids and tetracyanoethylene under conventional heating and microwave irradiation in solvent-free conditions. Excellent yield, very short reaction time (2–5 min), operatinal simplity, easy work-up procedure, avoidance of hazardous or toxic catalysts, and organic solvents are the main advantages of this green methodology which makes it more economic than the other conventional methods.     

New developments in polymer science and technology using combination of ionic liquids and microwave irradiation

The purpose of this review is to provide appropriate details concerning the application of ionic liquids (IL)s associated with microwave-assisted polymer chemistry. From the viewpoint of microwave chemistry, one of the key significant advantages of ILs is their high polarity, which is variable, depending on the cation and anion and therefore can effectively be tuned to a particular application. Hence, these liquids offer a great potential for the innovative application of microwaves for organic synthesis as well as for polymer science. ILs efficiently absorb microwave energy through an ionic conduction mechanism, and thus are employed as solvents and co-solvents, leading to a very high heating rate and a significantly shortened reaction time. Since an IL-based and microwave-accelerated procedure is efficient and environmentally benign, we believe that this method may have some potential applications in the synthesis of a wide variety of vinyl and non-vinyl polymers. This review describes application of combination of ILs with microwave irradiation as a modern tool for the addition and step-growth polymerization as well as modification of polymers and it was compared with ILs alone and conventional polymerization method.