US Patent 7371902 Methods for purifying p,p-bisphenol-A

Methods for purifying a p,p-bisphenol A generally include distilling a feed stream comprising p,p-BPA in a distillation column at a pressure less than or equal to 20 millibars. The distillation column separates the bisphenol feed stream to produce a light fraction, an intermediate fraction and a heavy fraction. The intermediate fraction comprising the purified bisphenol contains lesser impurities that the p,p-BPA in the feed stream. In one embodiment, the intermediate stream is recovered using a side-draw. The side-draw is located between a first zone and a third zone in the distillation column.