Bayer Materialscience Ag

Gert Tytgat

Michael Prein

Ulrich Blaschke

Raymond Audenaert

Christian Münnich

Rob Eek

Processes for producing bisphenols (e.g., bisphenol A (BPA)) having a purity greater than 99.7% are described, such processes including reacting a phenol and acetone in the presence of an acidic catalyst to form a product mixture comprising a bisphenol; removing at least a portion of the bisphenol from the product mixture in the form of a bisphenol/phenol adduct by crystallization, filtration and washing to provide bisphenol/phenol adduct crystals; and removing at least a portion of the phenol from the bisphenol/phenol adduct crystals to provide the bisphenol having a purity of more than 99.7%; wherein the crystallization comprises continuous suspension crystallization and is carried out in at least three crystallization devices arranged such that the product mixture is first cooled in a first stage of the crystallization to a temperature of 50 to 70&#xb0; C. in a first crystallization device and a second crystallization device connected in parallel, and subsequently cooled in a second stage of the crystallization to a temperature of 40 to 50&#xb0; C. in a third crystallization device connected downstream in series to the first and second crystallization devices, and wherein a total dwell time of the product mixture in the crystallization is more than 4 hours.

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Duffel, Belgium

Gert Tytgat