| 摘要 |
PURPOSE:To economically and advantageously obtain aromatic polyfunctional carboxylic acids useful as a monomer, etc., for polyimide resins from halogenated aromatic carboxylic acids in good yield and high selectivity in one step. CONSTITUTION:Halogenated aromatic carboxylic acids, preferably 4-halogeno-o- phthalic acids, 4-halogenonaphthalic acids or 4-halogenobenzoic acids are dehalogenated and dimerized in the presence of a catalyst containing Pd and a metal of a different kind, preferably Sn, Rh, Au, Ag or Pt, especially the Sn or Rh supported on a carrier in an alkaline aqueous solution containing a base, preferably oxide, carbonate or bicarbonate of an alkali metal or an alkaline earth metal, especially KOH and a reducing agent such as formic acid, a polyhydric alcohol, an amino-alcohol or CO present therein to afford the objective aromatic polyfunctional carboxylic acids. |
