Verfahren zur Herstellung von alpha-Methylstyrol mit einem Reinheitsgrad ueber 99,5%

摘要

1,239,185. α-Methylstyrene. PROGIL. 27 Jan., 1970 [28 Jan., 1969], No. 4010/70. Heading C5E. α-Methylstyrene having a purity greater than 99À5% is prepared by (a) vacuum distilling crude dimethylphenylcarbinol containing acetophenone and other impurities to give a bottoms fraction enriched with dimethylphenylcarbinol and acetophenone; (b) dehydrating the bottoms fraction in a single stage in liquid phase with a non-volatile catalyst; (c) distilling the product to give a distillate of water and α-methylstyrene; and (d) separating α-methylstyrene from the water by decantation. Stage (a) may be performed at 50-120 mm Hg. Stage (b) may be carried out at 180-230‹ C. in the presence of 0À01-0À5% sodium bisulphate.