| 摘要 |
PURPOSE:To obtain in high yield the titled compound useful as an intermediate for drugs, agricultural chemicals, etc., by decarboxylating 3,4,5,6- tetrafluorophthalic acid in an aqueous medium adjusted to a specific pH in the presence of a catalyst such as NH3, etc., at a specific temperature. CONSTITUTION:Preferably 3,4,5,6-tetrafluorophthalonitrile is hydrolyzed by the use of 30-90wt% aqueous solution of sulfuric acid at 100-180 deg.C to give 3,4,5,6-tetrafluorophthalic acid, which is decarboxylated in an aqueous medium such as water, etc., preadjusted to 0.7-2.2pH by the use of at least one compound selected from NH3, hydrosulfide, carbonate, bicarbonate, sulfate, organic acid salt and fluoride of alkaline(earth) metal, alkaline earth metal oxide, organic base and its sulfate as a catalyst at 100-220 deg.C at 0-15kg/cm<2>G while extracting an evolved CO2 gas to the outside of the system, to give the aimed compound. |
