| 摘要 |
2,4,5-trifluorobenzoic acid is prepared by converting 4,5-di-fluoroanthranilic acid to the corresponding amine salt, converting the amine salt to the corresponding diazonium tetrafluoroborate and decomposing the tetrafluoroborate in a Schiemann reaction. In a preferred preparation, the 10 percent HCl is added to solid 4,5-difluoroanthranilic acid in sufficient amount to dissolve the solid at 70 DEG C., the amine salt is isolated, aqueous NaNO2 is added to the isolated amine salt at 0 DEG C., followed by addition of 40 to 50 percent aqueous HBF4 at 0 DEG C., followed by separation of the tetrafluoroborate by cooling and filtering and then drying, and the dried separated tetrafluoroborate is thermally degraded to 2,4,5-trifluorobenzoic acid by heating at 125 DEG to 140 DEG C.
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