| 摘要 |
The invention comprises tetrafluorobenzene dicarboxylic acids and esters thereof; tetrafluorophthalic anhydride; 3,4,5,6-tetrafluorophthalimide; and 3,4,5,6-tetrafluoroanthranilic acid; the preparation of the acids by oxidation of the corresponding perfluoroxylenes with a strong acid; the preparation of the anhydride by refluxing tetrafluorophthalic acid with trifluoroacetic anhydride; the preparation of the imide by heating the anhydride with aqueous ammonia; the preparation of the anthranilic acid by subjecting the imide to Hofman degradation using bromine and aqueous caustic soda; and the preparation of dimethyl tetrafluorophthalate by esterifying the free acid with methanol using concentrated sulphuric acid as catalyst. Examples are given, tetrafluorophthalic acid being converted to di-(S-benzylthiouronium) tetrafluorophthalate, anilinium hydrogen tetrafluorophthalate and the di-silver salt, tetrafluorophthalimide being converted to a xanthydrol derivative, tetrafluoroanthranilic acid being converted to the S-benzyl-thiouronium compound, and tetrafluoroterephthalic acid being converted to a di-(S-benzylthiouronium) salt and a dianilinium salt. Decarboxylation of the acids to 1,2,3,4-tetrafluorobenzene and 1,2,4,5-tetrafluorobenzene is also described. Perfluoro-o-xylene is prepared by passing perfluoro-1,2-dimethylcyclohexane in a stream of nitrogen through a tube heated to 460 DEG C. and separating the product by gas-chromatography. Perfluoro-P-xylene is prepared similarly.ALSO:Polymers are formed by condensing glycols with tetrafluoroterephthalic acid and its esters. |
