| 摘要 |
In the prepn. of an aromatic dicarboxylic acid (I), an aromatic compd. contg. at least one alkyl, hydroxyalkyl or formyl group is oxidized in a primary oxidn. stage with O2 in a solvent in the presence of a heavy metal oxidn. catalyst, opt. in conjunction with an oxidn. promoter to produce a slurry of the (I) in the solvent. Before sepn. of the (I) from the mother liquor, fresh solvent and molecular oxygen are added to the slurry. The process is esp. useful for the prodn. of terephthalic acid from p-xylene in acetic acid solvent using a Co/Mn/Br catalyst. The content of p-carboxybenz-aldehyde as impurity is considerably reduced, which gives polyesters of improved colour.
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