Chlorination of benzidine and other aromatic amines in aqueous environments

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Abstract
The fate of aniline,N,N-dimethylaniline and benzidine in chlorinated waters was investigated. Conditions were controlled to approximate the process chlorination of raw water supplies and wastewater secondary effluents. As the molar ratio, (Cl2)/(amine), was increased, amine depletions increased and leveled off at about (Cl2)/(amine)=1. Depletions in distilled water with ‘free’ chlorine were somewhat higher than those in activated sludge/secondary effluent with combined chlorine. For each amine the number and type of products appeared to be independent of the water matrix and the ratio, (Cl2)/(amine). For the monophenyl amines ring chlorination was a significant depletion pathway. Extended chlorination of aniline yielded a precipitated product, while theN-substituted amine,N,N-dimethylaniline did not yield a solid product. In contrast to the monophenyl amines, when benzidine (p,p′-diaminobiphenyl) was exposed to chlorinated waters, a solid product resulted immediately. Infra-red analysis of this product indicated a polymeric structure with no ring chlorination. GLC analysis of the chlorination supernatant showed no ring substituted isomers of benzidine.