摘要

环保替代:干介质反应

作者(年代):阿舒·乔杜里，d .库马尔，r.v.辛格

绿色化学是研究的前沿领域，近年来一直是研究的重点。绿色化学，即减少或消除有害物质的使用和产生的化学产品和工艺的设计，是一种适用于化学的所有方面的首要方法。从原料到溶剂，再到合成和加工，绿色化学积极寻求以更有利于人类健康和环境的方式生产材料。当前对绿色化学的强调反映了一种转变，即从历史上的 - command-and-control -方法来解决环境问题，即通过法规强制进行废物处理、控制和清理，转向从源头上预防污染，而不是从源头上接受污染。绿色化学不接受废物的产生和处理是不可避免的，而是寻求更清洁和经济上有竞争力的新技术。利用绿色化学防治污染，展示了化学的力量和美丽:通过精心设计，社会可以享受我们所依赖的产品，同时造福环境。绿色化学的经济效益是其发展的核心驱动力。工业界正在采用绿色化学方法，因为它们提高了公司的底线。通过使用绿色化学，大量的运营成本都降低了。当产生的废物减少时，环保符合性就会下降。 Treatment and disposal become unnecessary when waste is eliminated. Decreased solvent usage and fewer processing steps lessen the material and energy costs of manufacturing and increase material efficiency. The environmental, human health, and the economic advantages realized through green chemistry are serving as a strong incentive to industry of adopt greener technologies. Solvents represent the single largest challenge to green chemistry. They are widely and intensively used in chemical and pharmaceutical processes, in formulation, cleaning and other sectors that the part of the modern industrial consumer society. Unfortunately many of the solvents are used in industry and retail are volatile organic compounds which inevitably lead to environmental damage, through pollution, risks to human health and to resource depletion, we need to develop and apply more environmentally friendly approaches. The fundamentally attractive concept of green chemistry is solvent free reactions. Solvent free reactions can be accelerated bymicrowave activation and this combined clean technology approach to “greening” chemical reactions. A solvent-free approach has been describes for organic synthesis which involves microwave (MW) exposure of neat reactants (undiluted) either in the presence of a catalyst or catalyzed by the surfaces of inexpensive and recyclable mineral supports such as alumina, silica, clay, or “doped” surfaces, namely,Fe(NO3)3-clay (clayfen),Cu(NO3)2-clay (claycop),NH2OH-clay, PhI(OAc)2- alumina, NaIO4-silica,MnO2-silica, and NaBH4-clay.Avariety of deprotection, condensation, cyclization, oxidation, and reduction reactions are presented including the efficient one-pot assembly of heterocyclic molecules from in situ generated intermediates such as enamines and -tosyloxyketones. The application of this solvent-free MW approach to multicomponent reactions is highlighted that can be adapted for high-speed parallel synthesis of the library of dihydropyrimidine-2(1H)-ones and imidazo 1,2-a]annulated pyridines, pyrazines, and pyrimidines.