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ENVIRONMENTALLY FRIENDLIER SYNTHESIS USING ALTERNATIVE REACTION CONDITIONS AND MEDIA
Citation:
Varma*, R S. ENVIRONMENTALLY FRIENDLIER SYNTHESIS USING ALTERNATIVE REACTION CONDITIONS AND MEDIA. Presented at AICHE/IIChE combined meeting, Mumbai, INDIA, December 28 - 30, 2004.
Impact/Purpose:
To inform the public
Description:
The diverse nature of chemical universe requires various 'greener' strategic pathways in our quest towards attaining sustainability. A solvent-free approach that involves microwave (MW) exposure of neat reactants (undiluted) catalyzed by the surfaces of less-expensive and recyclable mineral supports such as alumina, silica, clay, or 'doped' surfaces is presented which is applicable to a wide range of cleavage, condensation, cyclization, rearrangement, oxidation and reduction reactions including rapid one-pot assembly of heterocyclic compounds from in situ generated reactive intermediates. The strategy is adaptable to multi-component reactions e.g. Ugi and Biginelli reactions for rapid assembly of a library of compounds. Synthesis of a wide variety of significant precursors and intermediates namely, enones, imines, enamines, nitroalkenes, and oxidized sulfur species is depicted and their value in concise synthesis of flavones, tetrahydroquinolones, 2-aroylbenzofurans, and thiazole derivatives is illustrated.
Ultrasound- and MW-assisted solventless preparation of ionic liquids and their application in alkylation and metal-catalyzed multi-component reactions is described. Efficient reaction of epoxides with carbon dioxide, CO2, will be presented that provides ready access to cyclic carbonates using only a catalytic amount of recyclable ionic liquid as a catalyst.