Wednesday, June 25, 2008 Congressional Room (Capital Hilton) 101
Simple and Efficient Oxidation and α-Bromination of Benzylic Alcohols by Using Br2/UHP in Ionic Liquid
Jimi Kim and Jong Chan Lee. Chung-Ang University, Seoul, South Korea
The oxidation of alcohol to carbonyl compounds has been recognized as a fundamental organic transformation in organic synthesis. However, such transformations have been generally performed with environmentally hazardous inorganic oxidants, notably chromium(VI) reagents, pyridium dichromate and manganes reagents. Therefore, it is still desirable to develop a new efficient oxidation method for benzylic alcohols with properties of high stability and low toxicity. In these viewpoints, we investigated the feasibiltity of bromine/UHP in ionic liquid as green oxidation system. A mixture of aromatic ketones and bromine was heated and stirred in the presence of urea hydrogen peroxide in [bmim]BF4 ionic liquid. The carbonyl compounds were obtained within 1~3 hr at 50°C in high yield(70~90%). In cases of secondary alcohols, twice amount of bromine were required to give α-bromo Ketones. We have developed new alcohol oxidation conditions which are simple, mild, easy to handle.