Orthophthalates (India)

There are three isomers of phthalic acid: Orthophthalic acid (1,2- benzenedicarboxylic acid), Isophthalic acid (1,3-) and Terephthalic acid (1,4-). Orthophthalic acid , the only one of the three that can form an anhydride, is normally used in that form.