Organic compounds -- part of the class 532-570 series – Organic compounds – Sulfur containing
Patent
1986-12-12
1989-04-11
Ceperley, Mary E.
Organic compounds -- part of the class 532-570 series
Organic compounds
Sulfur containing
C07C14710
Patent
active
048208310
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for preparing 4,4'-dihydroxydiphenyl sulfone having a high purity.
BACKGROUND ART 4,4'-Dihydroxydiphenyl sulfone is excellent in resistance to
heat and oxidation, stability to light, etc. and is therefore an important chemical which is in increasing use in recent years as a substitute for bisphenol A in the field of plastics such as polyester resins, epoxy resins and polycarbonate resins. The 4,4'-dihydroxydiphenyl sulfone for such use must be at least 99% in purity.
The industrial processes heretofore known for producing 4,4'-dihydroxydiphenyl sulfone include one wherein phenol and sulfuric acid are subjected to a dehydration reaction. This process, however, gives a large amount of 2,4'-dihydroxydiphenyl sulfone as an isomer by-product along with 4,4'-dihydroxydiphenyl sulfone and involves difficulty in isolating 4,4'-dihydroxydiphenyl sulfone from the resulting isomer mixture, so that the products generally obtained invariably contain about 20 wt. % of the by-product. Accordingly, the 4,4'-dihydroxydiphenyl sulfone obtained by the process in no way fulfils the above requirement.
Various processes have therefore been proposed for preparing high-purity 4,4'-dihydroxydiphenyl sulfone. For example, Examined Japanese Patent Publications SHO 38-5274, SHO 43-24660, SHO 47-43936, etc. disclose processes wherein the 4,4'-dihydroxydiphenyl sulfone obtained by the above conventional process and containing a large amount of the isomer is recrystallized with a solvent. Any of these processes nevertheless relates to the separation and purification of the product resulting from the dehydration of phenol and sulfuric acid, accordingly inevitably permits the dehydration to produce about 20% of the isomer, consequently gives the desired 4,4'-dihydroxydiphenyl sulfone in a reduced yield and requires an additional purification procedure and further cumbersome treatment of the separated residue containing a large quantity of 2,4'-dihydroxydiphenyl sulfone.
DISCLOSURE OF THE INVENTION
Carrying out extensive research to overcome the foregoing drawbacks, we conceived of obaining 4,4'-dihydroxydiphenyl sulfone with a high purity in a high yield by improving the dehydration reaction itself between phenol and sulfuric acid and conducted a large number of experiments based on this concept. Consequently, we found it possible to prepare high-purity 4,4'-dihydroxydiphenyl sulfone in a high yield by a single process, by reacting phenol with sulfuric acid in the presence of a solvent for dehydration while almost completely isomerizing the resulting by-product 2,4'-dihydroxydiphenyl sulfone to 4,4'-dihdroxydiphenyl sulfone (see Examined Japanese Patent Publication SHO 55-8972 and corresponding U.S. Pat. No. 4,162,270). However, our subsequent research revealed that the dry solid product 4,4'-dihydroxydiphenyl sulfone obtained by this process, although almost free from the by-product 2,4'-dihydroxydiphenyl sulfone, contained as an impurity about 5 wt. % of trihydroxytriphenyl disulfone (hereinafter referred to as the "tri-compound"), i.e. the reaction product of phenolsulfonic acid and 4,4'-dihydroxydiphenyl sulfone or 2,4'-dihydroxydiphenyl sulfone, resulting from the dehydration reaction between phenol and sulfuric acid, that the tri-compound was difficult to separate from 4,4'-dihydroxydiphenyl sulfone and that the separation of the tri-compound from 4,4'-dihydroxydiphenyl sulfone relatively lowered the yield of 4,4'-dihydroxydiphenyl sulfone.
In view of the situation, we have made improvements in the above process and consequently found that the below-specified aromatic sulfonic acid, if present in the reaction system of phenol and sulfuric acid, makes it possible to almost completely isomerize the 2,4'-dihydroxydiphenyl sulfone resulting from the reaction to 4,4'-dihydroxydiphenyl sulfone and is also effective in greatly inhibiting formation of the tri-compound and in causing the dehydration reaction to proceed nearly 100%, consequently giving 4,4'-dihydroxydiphenyl su
REFERENCES:
patent: 3366692 (1968-01-01), Orem
Mitsubishi, Derwent Abstract of Japanese patent 50-116446, published Sep. 11, 1975.
Konishi, Derwent Abstract of Japanese patent 51-98239, published Aug. 39, 1976.
E. Ogata et al., Chemical Abstracts, vol. 85, No. 192367z (1976), Highly pure 4,4'-dihydroxydiphenyl sulfone.
Nate Nobuyuki
Ogata Eiji
Ono Koji
Ceperley Mary E.
Konishi Chemical Industry Co., Ltd.
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