Oxidation of aromatic aldehydes and ketones by H2O2/CH3ReO3 in ionic liquids: a catalytic efficient reaction to achieve dihydric phenols
Roberta Bernini*, Antonietta Coratti, Gianfranco Provenzano, Giancarlo Fabrizi and Daniela Tofani
*Dipartimento A.B.A.C, Università degli Studi della Tuscia, Via S. Camillo
De Lellis, 01100 Viterbo, Italy, Email: berninir
unitus.it
R. Bernini, A. Coratti, G. Provenzano, G. Fabrizi, D. Tofani, Tetrahedron, 2005, 61, 1821-1825.
DOI: 10.1016/j.tet.2004.12.025
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Abstract
A convenient and efficient oxidation of hydroxylated and methoxylated benzaldehydes and acetophenones to the corresponding phenols uses hydrogen peroxide and methyltrioxorhenium as catalyst in ionic liquids [bmim]BF4 and [bmim]PF6.
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Details
The study explores the oxidation of hydroxylated and methoxylated benzaldehydes and acetophenones to dihydric phenols using hydrogen peroxide/methyltrioxorhenium (H2O2/CH3ReO3) in ionic liquids [bmim]BF4 and [bmim]PF6. This method offers a convenient and efficient alternative to traditional synthesis routes, achieving good yields in short reaction times. The ionic liquids used exhibit low volatility, stability, and recyclability, enhancing the reaction's efficiency. The research demonstrated that the nature of the ionic liquid anion does not significantly impact the reaction's reactivity or time. The catalytic system remained stable and efficient for up to five recycling experiments. The study also found that while activated benzaldehydes yielded good results, meta-substituted electron-donating groups and unsubstituted benzaldehydes primarily produced benzoic acids instead of the desired phenols. Additionally, the oxidation of aromatic ketones required higher temperatures (80°C) to achieve good yields. Overall, the H2O2/CH3ReO3 system in ionic liquids proved to be a promising method for synthesizing dihydric phenols, with ongoing work to test its chemoselectivity in more complex molecules.
Key Words
Dakin Reaction, Carboxylic Acids, Hydrogen Peroxide, Rhenium, Methyltrioxorhenium, Ionic Liquids
ID: J72-Y2005-2830
