The synthesis of D,L-alpha-tocopherol in supercritical media

The synthesis of D,L-alpha-tocopherol in supercritical carbon dioxide or ni trous oxide by condensation of trimethylhydroquinone (TMHQ) with isophytol (IP) in the presence of various Bronsted or Lewis acids, especially an imid e or its metal salts, as catalysts is described. The product is obtained in high yield. The method represents an interesting alternative to existing p rocesses. A quasi-reaction mechanism is being proposed together with kineti cs, which are needed for the reactor analysis and design. (C) 2000 Elsevier Science B.V. All rights reserved.