Benzenedicarboxylic acid is a group of chemical compounds which are dicarboxylic derivatives of benzene. Benzenedicarboxylic acid comes in three isomers:
Phthalic acid (1,2-benzenedicarboxylic acid) Isophthalic acid (1,3-benzenedicarboxylic acid) Terephthalic acid (1,4-benzenedicarboxylic acid)
All isomers share the molecular weight 166.13 g/mol and the chemical formula C8H6O4.