Process for the production of bisphenol A
First Claim
1. A process of producing bisphenol A, comprising the steps of:
- providing a crystalline adduct of bisphenol A and phenol which has an APHA color of not greater than 15 and which shows a pH of 4.9-5.5 when dissolved in an aqueous methanol solution having a pH of 5;
melting said adduct in an atmosphere having an oxygen concentration of 0.005% by volume or less to obtain a melted adduct; and
vaporizing and removing phenol from said melted product to leave bisphenol A.
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Abstract
High quality bisphenol A is produced from a neutral crystalline adduct of bisphenol A and phenol by fusing the adduct in an atmosphere having a maximum oxygen content of 0.005% by volume, followed by evaporation of liberated phenol. The crystalline adduct may be mixed with an aliphatic carboxylic acid before the fusion to reduce the coloring of the product. When an acidic crystalline adduct is used, the use of a strong alkali salt of an aliphatic carboxylic acid is suitably used. Interior surfaces of the apparatuses for carrying out the fusion and evaporation are desirably washed with an organic solvent to remove oxygen therefrom. The evaporation of phenol is suitably performed by two stage steam stripping wherein a used stripping gas obtained in the second stage is employed as a stripping gas in the first stage while steam is used as the stripping gas in the second stage.
20 Citations
6 Claims
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1. A process of producing bisphenol A, comprising the steps of:
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providing a crystalline adduct of bisphenol A and phenol which has an APHA color of not greater than 15 and which shows a pH of 4.9-5.5 when dissolved in an aqueous methanol solution having a pH of 5; melting said adduct in an atmosphere having an oxygen concentration of 0.005% by volume or less to obtain a melted adduct; and vaporizing and removing phenol from said melted product to leave bisphenol A.
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- 2. A process of producing bisphenol A, wherein a crystalline adduct of bisphenol A and phenol having an APHA color of not greater than 15 is fed to a melting zone to melt said adduct and the melted adduct is introduced into a separation zone to separate the melted adduct into phenol and bisphenol A by evaporation of the phenol from said melted adduct, said process being characterized in that the interior surfaces of said melting zone and said separation zone which are to be contacted with said melted adduct or the phenol separated from said melted adduct are previously washed with an organic solvent for the removal of oxygen gas entrapped in said interior surfaces so that the interior surfaces have an oxygen content of 10 mmoles or less per 1 m2 thereof.
- 4. A process of producing bisphenol A, wherein a melted crystalline adduct of bisphenol A and phenol having an APHA color of not greater than 15 is introduced into a separation zone to separate the melted adduct into phenol and bisphenol A by evaporation of the phenol from said melted adduct, said process being characterized in that said separation zone is provided with a member for increasing the area of the surface with which said melted crystalline adduct is to be contacted, and that the interior surface of said separation zone and the surface of said member are previously treated for the removal of oxygen gas entrapped thereon so that the inside surface of said separation zone and the surface of said member have an oxygen content of 10 mmoles or less per 1 m2 thereof.
Specification