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ENVIRONMENTALLY FRIENDLIER SYNTHETIC ALTERNATIVES USING NON-TRADITIONAL APPROACHES
Citation:
Varma*, R S. ENVIRONMENTALLY FRIENDLIER SYNTHETIC ALTERNATIVES USING NON-TRADITIONAL APPROACHES. Presented at Chemistry Faculty, Universidad de Castilla-La Mancha, Ciudad Real, SPAIN, September 26, 2002.
Impact/Purpose:
To inform the public.
Description:
Synthetic organic transformations performed under non-traditional conditions are becoming popular primarily to circumvent the growing environmental concerns. A solvent-free approach that involves microwave (MW) exposure of neat reactants (undiluted) either in presence of a catalyst or catalyzed by the surfaces of less-expensive and recyclable mineral supports such as alumina, silica, clay, or 'doped' surfaces is forwarded 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 for multi-component reactions for rapid assembly of a library of compounds. Ultrasound-assisted solventless protocol is presented that provides ready access to non-volatile solvents, ionic liquids. 'Greener' solvents such as supercritical (sc) carbon dioxide provides an attractive media for supported metallic catalysts such as Pd/alumina for industrially significant transformations such as selective hydrogenation of maleic anhydride to g-butyrolactone. The salient eco-friendly features of these processes namely the selectivity, experimental ease of manipulation, and the enhanced reaction rates will be described.