Dihexyl phthalate (DHP, 1,2-benzenedicarboxylic acid, dihexyl ester phthalic acid) is clear oily liquid with slight odour. Soluble in petroleum ether, benzene, chloroform; almost insoluble in water.
Dihexyl phthalate is produced by esterification of phthalic anhydride with n-hexanol in presence of benzenesulfonic acid as a catalyst. Then mixture is neutralized with water alkali hydroxides or carbonates; the excess n-hexanol is recovered and recycled by treatment with superheated steam; dihexyl phthalate is purified by activated charcoal.
Dihexyl phthalate is used as plasticizer for PVC (polyvinylchloride), rubbers and cellulose esters.