Aryl diazonium salts are easily prepared, common and highly applicable intermediates in the synthetic organic chemistry because of their high reactivity and varied reactions. They are synthesized starting from primary aromatic amines by diazotization and coupling with aromatics like phenols (or primary aromatic amines). Azo dyes are industrially very important for technical purposes. Azo compounds have many applications like acts as pigments, antioxidants, the polymeric biodegradable pro-drugs and many used in food, cosmetics and drug industry as synthetic colorants. The present review highlights’ the literature involving diazonium salts as active intermediate for preparation of synthetically useful phenolic derivatives used up to 2010 with their applications and biological activities.
