Bis(4-hydroxyaryl)alkanes
View Patent ↗The present application relates to a process for producing high-purity bis(4-hydroxyaryl)alkanes from adducts of bis(4-hydroxyaryl)alkanes and aromatic hydroxy compounds, which are obtained by acid-catalysed reaction of the aromatic hydroxy compounds with ketones.
1. A process for separating bis(4-hydroxyaryl)-alkanes from adducts of bis(4-hydroxyaryl)alkanes having aromatic hydroxy compounds, which is characterised in that the crystallised, filtered-off and purified bis(4-hydroxyaryl)alkane/arylhydroxy adducts) arising during the acid catalyzed reaction of aromatic hydroxy compounds with ketones are melted under product-protective conditions and separated by desorption of the aromatic hydroxy compounds said desorption by nitrogen gas.
2. A process according to claim 1 , characterised in that 2,2-bis(4-hydroxyphenyl)propane is separated from 2,2-bis(4-hydroxyphenyl)propane/phenol adducts.
3. A process according to claim 2 , characterised in that the quantity of gas introduced into the desorber amounts preferably to from 100 to 300 m 3 per m 3 of BPA/phenol adduct mixture and the gas temperature is above 160° C. to 230° C.
4. A process according to claim 1 , characterised in that the nitrogen is recirculated after desorption by cooling and separation of the phenol.
5. A device for separating bis(4-hydroxyaryl)alkanes and aromatic hydroxy compounds from bis(4-hydroxyaryl)alkane/arylhydroxy adducts arising from the acid-catalyzed reaction of aromatic compounds with ketones, characterised by a desorber ( 1 ), which contains tube bundle heat exchangers and wherein the spaces between the heat exchanger tubes are filled on the product side with ceramic spheres and the product chamber is mainly filled with liquid and wherein the heat exchangers are arranged upright and provided at their lower part with a number of nozzles, via which a hot inert gas may be introduced, having a means for diverting the phenol, once distilled off, and the gas to a condenser ( 2 ) and a phenol collecting receiver ( 3 ) connected thereto, together with a scrubbing tower ( 4 ) connected to the phenol collecting receiver and optionally filters ( 5 ) for cleaning the gas leaving the condensers ( 2 ) and separators ( 3 ) and a means of returning the gas to the desorber ( 1 ).
6. The process of claim 4 wherein 1-5% of the gas is discharged from the recirculated stream.
7. The process of claim 1 wherein the desorption is preceded by distillation.