| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for inexpensively producing slightly discolored pyromellitic dianhydride with low contents of monoanhydrides, etc., of aromatic dicarboxylic acids or aromatic tricarboxylic acids or the monoanhydrides such as pyromellitic monoanhydride and having particle properties of causing no clogging of reactors, transfer containers and pipes, etc. SOLUTION: The method for producing the pyromellitic dianhydride comprises the following steps. A step of thermally dehydrating crude pyromellitic acid in the absence of acetic anhydride, converting 50.0-99.5 wt.% of the pyromellitic acid into the pyromellitic dianhydride and affording a reaction mixture containing at least the pyromellitic acid and the pyromellitic dianhydride and a step of thermally dehydrating the reaction mixture in the presence of the acetic anhydride. COPYRIGHT: (C)2007,JPO&INPIT
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