Chlorination of benzidine and other aromatic amines an aqueous environments

Area of Science:

• Environmental Chemistry
• Water Treatment Technologies
• Organic Chemistry

Background:

• Chlorination is a common method for water disinfection.
• Understanding the fate of organic contaminants during chlorination is crucial for water safety.
• Aniline, N,N-dimethylaniline, and benzidine are relevant organic compounds found in water sources.

Purpose of the Study:

• To investigate the reaction pathways and products of aniline, N,N-dimethylaniline, and benzidine during chlorination.
• To compare the behavior of these amines in different water matrices (distilled vs. wastewater effluent).
• To determine the influence of the chlorine-to-amine molar ratio on the depletion and product formation.

Main Methods:

• Controlled chlorination experiments simulating water treatment processes.
• Analysis of amine depletion using varying molar ratios of chlorine to amine.
• Identification of reaction products using Infra-red (IR) spectroscopy and Gas-Liquid Chromatography (GLC).

Main Results:

• Amine depletion increased with the chlorine-to-amine ratio, plateauing around a 1:1 ratio.
• Ring chlorination was a significant pathway for monophenyl amines (aniline and N,N-dimethylaniline).
• Benzidine formed an immediate solid, polymeric product without ring chlorination, unlike the other amines.

Conclusions:

• The chlorination of aniline and N,N-dimethylaniline leads to ring-substituted products, with aniline forming a precipitate.
• Benzidine undergoes a distinct polymerization reaction upon chlorination, forming a solid product without ring substitution.
• The water matrix (distilled vs. effluent) had a minor effect on amine depletion and product type.