Process for the preparation of 3,3',4,4'-biphenyltetracarboxylic acid and its derivatives
US5081281A · kind A · utility
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4References
28Claims
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Key dates
| Filing date | Oct 6, 1989 |
| Grant date | Jan 14, 1992 |
| Priority date | — |
| Expiry date | Oct 6, 2009 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C67/343
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
Biphenyl tetracarboxlic acid esters and derivatives thereof are prepared by the coupling reaction of 4-halogen substituted o-benzenedicarboxylic acid ester, carried out in an aprotic polar solvent in the presence of a pre-prepared triphenylphosphine-nickel chloride or trialkylphosphine-nickel chloride catalyst, zinc powder as the reducing agent, and an alkali metal halide promoting agent. The ester may be hydrolyzed in basic solution to afford the corresponding acid. The acid may be heated or boiled with acetic anhydride to afford the biphenyl dianhydride.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.