Process for producing highly pure 3,3',4,4'-biphenyltetracarboxylic acid
申请人:Hitachi, Ltd.
公开号:US05047560A1
公开(公告)日:1991-09-10
Highly pure 3,3',4,4'-biphenyltetracarboxylic acid (BPTA) and dianhydride thereof (BPDA) are produced by heating crude BPTA to give BPDA, treating the BPDA with hot water to give highly pure BPTA, and in the case of highly pure BPDA, heat treating the pure BPTA to give highly pure BPDA.