Process for producing biphenyltetracarboxylic dianhydrides
US3940426A · kind A · utility
11Cited by
4References
3Claims
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Key dates
| Filing date | Jan 16, 1973 |
| Grant date | Feb 24, 1976 |
| Priority date | — |
| Expiry date | Jan 16, 1993 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C67/343
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A process for separating and purifying biphenyltetracarboxylic dianhdride isomers from a mixture of these isomers by fractional crystallization in aliphatic acid anhydrides or acetone. The isomeric mixture is obtained by heating biphenyltetracarboxylic acids, optionally in the presence of an aliphatic acid anhydride. The biphenyltetracarboxylic acids are obtained by oxidizing coupling dimers of o-xylene or by hydrolyzing coupling dimers of dimethyl phthalate.
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