| 摘要 |
PURPOSE:To obtain the titled readily handleable substance having a large crystal size directly without using dehydration reaction in a liquid medium, by heating and evaporating a biphenyltetracarboxylic acid dianhydride under specific conditions, and cooling the evaporated vapor. CONSTITUTION:Crude biphenyltetracarboxylic acid dianhydride is heated and evaporated under <=30mmHg, preferably <=20mmHg reduced pressure at 250-400 deg.C, preferably 300-350 deg.C temperature, and the evaporated vapor of the biphenyltetracarboxylic acid dianhydride is cooled normally to <=200 deg.C, preferably <=100 deg.C, purified and crystallized to give the titled substance. Preferably, biphenyltetracarboxylic acid obtained by hydrolyzing tetramethyl biphenyltetracarboxylate prepared by dehydrodimerization of dimethyl o- phthalate in an aqueous medium, is subjected to dehydration reaction at 150-230 deg.C under reduced pressure and the above-mentioned reaction is carried out.
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