| 摘要 |
<p>Phenol derived from cumene is purified by subjecting the impure phenol to fractional distillation to remove acetone, heating the substantially acetone - free phenol - containing material under acid conditions with an acid catalyst until the benzofuran content of the reaction mixture has been reduced to a practical minimum, and subjecting the reaction mixture to fractional distillation to recover a purified phenol-containing material. The phenol starting material may be subjected to fractional distillation to remove both high-boiling and low-boiling impurities before being treated as above. Suitable catalysts include mineral acids, strong organic acids, acidic clays, acidic ion exchange resins, boron trifluoride and the halides, sulphates and nitrates of copper, chromium, mercury, platinum, zinc, cadmium, gallium, vanadium and the metals of Group IV and VIII of the Periodic Table having an atomic number less than 52, the preferred catalysts being those of the Friedel-Crafts type. The amount of catalyst is generally in the range 0.005% to 5% by weight based on the weight of phenol-containing material. The process takes place between 40 DEG C. and 182 DEG C. at atmospheric pressure, but pressures higher or lower than atmospheric may be used. It is desirable to have as little water present as is practical. The process may be applied to a phenol which has been treated with a base as in Specification 883,746 and fractionally distilled to remove reaction products from the phenol before being heated in the presence of the catalyst. Detailed examples are given in which the acid catalysts used are ferric chloride, sulphuric acid, chromic chloride, mercuric chloride, acid-treated bentonite, p-toluene sulphonic acid and platinum chloride. Other specific catalysts are mentioned. Specification 865,677 also is referred to.</p> |
