Spectrophotometric Determination of Aromatic Amines by the Diazotization-Coupling Technique with 8-Amino-1-hydroxynaphthalene-3,6-disulfonic Acid and N-(1-Naphthyl)ethylenediamine as the Coupling Agents

Article abstract of DOI:10.1021/ac00241a049

A comprehensive study is made of the application of the diazotization-coupling spectrophotometric technique to the determination of diverse aromatic amines, using H-acid (8-amino-1-hydroxynaphthalene-3,6-disulfonic acid) and N-(1-naphthyl)ethylenediamine (also called N-(1-naphthalenyl)-1,2-ethanediamine or N-na) as the coupling agents.The methods were tested successfully on halogenate anilines, 2,4-dichloroaniline, nitroanilines, methylanilines, aminobenzoic acids, aminobenzenesulfonic acids, sulfanilamide, and certain other substituted anilines.The methods are not rec ommended for phenylenediamines and aminophenols, which produce little or no color.The aromatic amines containing negative groups tend to couple and produce colors more readily than aromatic amines not containing such groups.The amount of reagent and time required for full color development is less for aromatic amines containing negative groups, specially for the N-na method.Both methods are about equal in accuracy but the N-na mathod is on the average about 1.6 times more sensitive than the H-acid method.