Patent ID: 8859801

Claim:
A method for producing a 3,4-dicarboalkoxybiphenyl-3′,4′-dicarboxylic acid (including the corresponding acid anhydride) represented by a general formula (1-1), wherein the method comprises oxidizing a 3,4-dialkylbiphenyl-3′,4′-dicarboxylic acid compound represented by a general formula (2) or a 3,4-dimethylbiphenyldicarboxylic acid compound represented by a general formula (3) (hereinafter referred to as an oxidation): wherein in general formula (1-1), R 1 and R 2 each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and n represents the number of waters of hydration that is 0 or 1, in general formula 2 R 1 and R 2 each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R 3 and R 4 each represents an alkyl group having 1 to 4 carbon atoms, and in general formula (3), R 1 and R 2 each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.