A green alternative to synthetize azo compounds

Different nitrates were used as sources of nitrosonium ion to obtain diazonium salts. Diverse azo compounds were synthetized in acetonitrile giving very good yields and free of by-products in comparison with traditional synthesis. Among the tested species, the best combination for para red synthesis was nitric acid and gaseous hydrogen chloride.

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► Azo dyes derived of β-naphthol can be synthesized in organic media with good yields.
► The use of organic solvent broad the scope of the technique to highly insoluble amines.
► In this procedure no by-products are formed.
► Compared to traditional synthesis, this methodology has better Green metrics.