A spectrophotometric study of the colour reaction between chloranil and aromatic amines

The colour reaction between aromatic amines and chloranil was studied spectrophotometrically. A 1 : 1 adduct formed in solution, with some dissociation. The effects of solvents, acid and alkali were examined. The adducts exhibited intense, and characteristic, broad absorption bands, which could be used for the detection and estimation of an aromatic amine, in the absence of substances of similar light absorption characteristics. A correlation between the basicities of an amine and the ight absorption of the adduct was established.