PURPOSE: To obtain the titled compound, having low hygroscopicity and useful as a raw material for polyimides, etc., by heating benzophenonetetracarboxylic acid in the presence of a solvent consisting essentially of a specific organic compound, inert to the benzophenonetetracarboxylic acid and anhydride thereof and having a specific boiling point.
CONSTITUTION: A compound expressed by formula I is heated normally at 180W250°C, preferably 200W250°C, particularly 210W230°C in the presence of an organic compound, inert to compounds expressed by formulas IWII and having >100°C point and normally <100°C melting point, preferably ≥180°C boiling point and ≤70°C melting point, e.g. an aromatic compound, aliphatic hydrocarbon or ether compound, preferably the ether compound or 10W30C aromatic compound, particularly a mixed solvent of 70W75wt% diphenyl ether and 25W30wt% diphenyl to afford the aimed compound of high purity, expressed by formula III and containing no impurity harmful to polycondensation reaction of the compounds expressed by formulas I and II, etc.
ANDO NAOKI
HOSOYA KENJI
