| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a catalyst/solvent matrix needing no addition of an expensive new catalyst after condensation and capable of carrying out both the condensation and an after-acylation at medium temperatures. SOLUTION: A method for preparingα-tocopherol acetate in a recycling method comprises the following processes: trimethylhydroquinone is made to condense with isophytol in a mixture of a polar solvent, which is extractable with water or miscible with water, and water in the presence of a catalyst system consisting of zinc halide and an aqueous protonic acid, and optionally an elemental metal; successively, the resultantα-tocopherol is acylated; and the catalyst system is recycled.</p> |
