How is 4-Bromo-3-chloro-1,2-benzenediamine (CAS: 1008361-80-5) typically synthesized?

4-Bromo-3-chloro-1,2-benzenediamine is typically synthesized by introducing bromine and chlorine substituents onto a diamine precursor through electrophilic aromatic substitution. Common methods include the bromination of 3-chloro-1,2-benzenediamine followed by selective chlorination. The reaction is usually catalyzed by Lewis acids or halide salts at elevated temperatures, with high yields and good selectivity achievable under optimized conditions.