Preparation of alpha-tocopherol or alpha-tocopheryl acetate

摘要

Preparation of alpha -tocopherol or alpha -tocopheryl acetate comprises reaction of 2,3,5-trimethylhydroquinone (TMH) with phytol or isophytol (IP) in the presence of zinc chloride and a proton donor in a water immiscible, or poorly water miscible, nonpolar solvent; and the product is optionally esterified with acetic anhydride. Either (1) the ZnCl2 is used in a mixture with 1-4 moles water per mole ZnCl2; or (2) at the end of reaction, the zinc chloride is separated, preferably by extraction with water or a water/low-boiling solvent mixture; and the zinc chloride solution (optionally concentrated to 60-90 wt.%), is partly or completely returned (optionally as a hot solution or pumpable mash) to the reaction mixture under conditions such that no more than 4 (preferably no more than 3) moles water per mole zinc chloride are available for subsequent reaction.