4,4'-[(1-methylethylidene)bis(1,4-phenyleneoxy)]bisphthalic acid 4,4'-[(1-Methylethylidene)bis(4,1-phenyleneoxy)]bis(1,2-benzenedicarboxylic acid) 4,4'-[(Dimethylmethylene)bis(4,1-phenyleneoxy)]bisphthalic acid 4,4'-[Dimethylmethylenebis(4,1-phenyleneoxy)]bisphthalic acid 4,4'-[Isopropylidenebis(1,4-phenyleneoxy)]bisphthalic acid 4,4'-[Isopropylidenebis(4,1-phenylene)bisoxy]bisphthalic acid 4,4'-[Isopropylidenebis[(4,1-phenylene)oxy]]bisphthalic acid