Phthalates or phthalate esters are esters of phthalic acid and are chiefly used as plasticizers. Phthalates are manufactured by reacting phthalic anhydride with alcohol that range from methanol and ethanol up to tridecyl alcohol, either as a straight chain or with some branching. They are divided into two distinct groups, with very different applications, toxicological properties, and classification, based on the number of carbon atoms in their alcohol chain.