Abstrakt

Environmentally eco-friendly alternate : Dry media reactions

Ashu Chaudhary, D.Kumar, R.V.Singh

Green Chemistry is placed in the frontier areas of research and has been focused for considerable recent research. Green Chemistry, the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances is an overarching approach that is applicable to all aspects of chemistry. From feedstocks to solvents, to synthesis and processing green chemistry actively seeks ways to produce materials in a way that is more begin to human health and the environment. The current emphasis on green chemistry reflects a shift away from the historic “command-and-control” approach to environmental problems that mandated waste treatment, control and clean up through regulation and towards preventing pollution at its source rather than accepting pollution at its source. Rather than accepting waste generation and disposal as unavoidable, green chemistry seeks newtechnologies that are cleaner and economically competitive. Utilizing green chemistry for pollution prevention demonstrates that power and beauty of chemistry : through careful design, society can enjoy the products on which we depend while benefiting the environment. The economic benefits of green chemistry are central drivers in its advancement. Industry is adopting green chemistry methodologies because they improve the corporate bottom line. A wide array of operating costs are decreased through the use of green chemistry. When less waste is generated, environmental compliance casts go down. 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.