Synthesis of symmetric and asymmetric 1,3-diaryltriazenes in vinegar

An adaptation on the classical synthesis methodology for 1,3-diaryltriazenes for a 4-hour experimental class has been proposed with green chemistry principles in mind by using commercial vinegar as a source for diazotization with NaNO₂ and keeping the reaction workup to simple vacuum filtration. Several anilines with different substituent groups were used to evaluate how they affect the synthesis based on their electron-donating/withdrawing characteristics. The decomposition of the triazenes in acidic media was also monitored via TLC. On the overall, the reactions came up with medium to high yield and high purity. Experimental procedure, reaction mechanism and other potential discussions such as green chemistry principles and effects of electron-donating/withdrawing groups are suitable for undergraduate students.

Keywords:
organic chemistry; green chemistry; anilines; triazenes; vinegar