| 摘要 |
<p>PURPOSE:To suppress low-boiling compound formed as a by-product and obtain the titled compound in good yield, by continuously subjecting an o-phthalic acid diester to dimerization reaction in the presence of a catalyst containing a bivalent palladium salt while feeding a gas containing molecular oxygen to the reaction system. CONSTITUTION:An o-phthalic acid diester (e.g. dimethyl o-phthalate) is heated in the absence of a solvent in the presence of a catalyst containing a bivalent palladium salt (e.g. palladium acetate) at 140-260 deg.C under ordinary pressure while feeding a gas containing molecular oxygen to the reaction system. Low- boiling compounds formed as a by-product in the reaction, together with part of the o-phthalic acid diester, are continuously distilled away to the outside of the reaction system and the o-phthalic acid diester is supplied to the reaction system to carry out dimerization reaction. The aimed substance is useful as a raw material for monomers of aromatic polyimides.</p> |
