Jun 26, 2014 |
A breakthrough for organic reactions in water
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(Nanowerk News) Green-chemistry researchers at McGill University have discovered a way to use water as a solvent in one of the reactions most widely used to synthesize chemical products and pharmaceuticals.
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The findings, published June 26 in Nature Communications ("The Barbier-Grignard-Type Carbonyl Arylation Using Unactivated Aryl Halides in Water"), mark a potential milestone in efforts to develop organic reactions in water.
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Chao-Jun Li and Feng Zhou of McGill’s Department of Chemistry report that they have discovered a catalytic system which for the first time allows direct metal-mediated reactions between aryl halides and carbonyl compounds in water.
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For the past two decades, researchers have been exploring ways to do away with chemists’ traditional reliance on non-renewable petrochemical feedstocks and toxic solvents. One important method has involved replacing the toxic solvents used in metal-mediated reactions with water – something that was previously considered impossible.
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While researchers at McGill and elsewhere have succeeded in using water in metal-mediated reactions between carbonyl compounds and other halides, attempts to do so for the most challenging reaction, between aryl halides and carbonyl compounds, have never worked – until now.
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Prof. Li and Dr. Zhou, a postdoctoral fellow, found that rhodium -- a metal primarily used in the catalytic converters of automobiles -- as a catalyst together with zinc as a mediator can make the reaction possible in water. This new technique bypasses a number of challenges posed by conventional practices in carrying out this reaction, which is widely used in synthesizing fine chemicals, biologically active molecules and pharmaceuticals. Traditional methods, discovered more than a century ago, require that moisture and air be carefully excluded from the process.
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The new aqueous approach promises to “streamline synthetic sequences and make them safer and more efficient,” said Prof. Li, Canada Research Chair in Green Chemistry.
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