Patent ID: 6806394
Filing Date: 2004-10-19
Classification: C07C

Abstract:
A process for producing and purifying p,pâ€²-bisphenol A comprising the steps of:(a) reacting acetone with a stoichiometric excess of phenol under acidic conditions to form a reaction product stream consisting essentially of crude p,pâ€²-bisphenol A product, unreacted phenol, possibly unreacted acetone, water of condensation, and other reaction byproducts; (b) distilling the reaction product stream from step (a) to distill off a volatilized unreacted phenol stream, possibly an unreacted acetone stream, and the water of condensation, while sending a BPA liquid feed stream consisting essentially of concentrated bisphenol A together with remaining unreacted phenol and higher boiling point reaction byproducts downstream to a multistage phenol adduct crystallization and purification process; (c) producing first-stage phenol adduct crystals by crystallization in the crystallization step of the first of at least two in-series BPA purification stages, each comprising a crystallization step and a solid-liquid separation and wash step; (d) washing the first-stage phenol adduct crystals with a high purity wash phenol stream, which includes at least a portion of the volatilized unreacted phenol stream recovered from step (b), said wash phenol stream being substantially free of bisphenol isomers and other impurities, to produce first-stage washed phenol adduct, first-stage spent wash, and first-stage mother liquor; (e) sending the first-stage washed phenol adduct to a second purification stage for producing second-stage phenol adduct crystals; and, (f) washing the second-stage phenol adduct crystals with a high purity wash phenol stream which is substantially free of bisphenol isomers and other impurities to produce second-stage washed phenol adduct, second-stage spent wash, and second-stage mother liquor.