| 摘要 |
<p>Disclosed is a method for preparing DL-α-tocopherol through the condensation of isophytol or phytol derivatives and trimethylhydroquinone(TMHQ) using a catalyst system comprising a divalent metal halogen compound, silica gel and/or silica-alumina, and a Bronsted acid. Isophytol or phytol derivatives are slowly added to trimethylhydroquinone for the condensation thereof at 80 to 135 °C over 30 to 60 min in the presence of the metal halogen and the silica gel and/or silica-alumina. In the presence of the Bronsted acid, the intermediates are converted into the product. The silica gel and/or silica-alumina is washed with a polar solvent for recovery. The catalyst system can remarkably reduce side-reactions upon the condensation of isophytol or phytol derivatives and TMHQ, thus producing DL-α-tocopherol with a high purity at a high yield. Also, the catalyst system can be regenerated in succession because of its being able to avoid the decrease of catalytic activity attributed to the adsorption of organic materials; thus reducing the production cost of DL-α-tocopherol and the quantity of industrial wastes generated. With these advantages, the catalyst system can be effectively used in preparing highly pure DL-α-tocopherol at a high yield on a commercial scale.</p> |
