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PREPARATIONS AND REACTIONS OF RIEKE METALS ACTIVATED ALUMINUM AND ZINC
Abstract
In 1972, Dr. Reuben Rieke published his first paper on the activated metal research in the Journal of American Chemical Society. Since then, a total of nineteen papers on this subject have appeared in the literature, not including several other papers which are in the process of publishing. The basic Rieke procedure for the preparation of activated metals is now generally described as "the reduction of an anhydrous metal salt in a hydrocarbon or ethereal solvent under inert atmosphere with or without additives". The Rieke activated metal research is an important part of an extremely vital area of chemistry which involves the reaction of organic and inorganic substrates at a metal surface, either in a catalytic fashion or with the consumption of the metal. These Rieke activated metals are extremely reactive. In this study, the reduction conditions are found to have profound effects on the reactivity of these powders. The best combination of reagents for the preparation of aluminum, is AlCl(,3)-K-Xylenes; for zinc, the best combination is ZnCl(,2)-Li-Naphthalene-Glyme. Both metals are reactive toward arylhalides. The Rieke aluminum metal reacts with carbonyl compounds in various ways, depending on the reaction condition. When the reaction with benzophenone is conducted in xylenes, a hydrocarbon solvent, tetraphenyloxirane is the major product in the unquenched reaction solution. When this reaction is performed in tetrahydrofuran, an ethereal solvent, it proceeds to give high yields of benzopinacol after quenching. In pyridines, tetraphenylethylene is also produced in addition to benzopinacol. A variety of related compounds have also been identified in various attempts, depending on the reduction and reaction conditions. The application of Rieke aluminum metal in the pinacol synthesis is also successfully extended to acetophenone, cyclohexanone and benzaldehyde. The Fischer-Hafner synthesis of bis-(PI)-benzenechromium can also be realized by using the Rieke aluminum powders with large excess of aluminum chloride in the presence of chromium trichloride and benzene. The lithium-naphthalene reduction procedure of the Rieke method allows the production of zinc metal with unusual reactivity. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI
Subject Area
Organic chemistry
Recommended Citation
LI, PERCY TZU-JUNG, "PREPARATIONS AND REACTIONS OF RIEKE METALS ACTIVATED ALUMINUM AND ZINC" (1981). ETD collection for University of Nebraska-Lincoln. AAI8228151.
https://digitalcommons.unl.edu/dissertations/AAI8228151