| 摘要 |
A process for preparing 3,4,3',4'-benzophenonetetracarboxylic dianhydride which comprises condensing an impure ortho-xylene mixture with acetaldehyde in contact with an acid catalyst to obtain an impure 1,1-bis(3,4-dimethylphenyl)ethane mixture, oxidizing the 1,1-bis(3,4-dimethylphenyl)ethane mixture with nitric acid to obtain a mixture of carboxylic acids, from which by crystallization and dehydration substantially pure 3,4,3',4'-benzophenonetetracarboxylic dianhydride is recovered.
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