BF3.SiO2: an efficient catalyst for the synthesis of azo dyes at room temperature

A rapid one-pot method has been developed for the synthesis of azo dyes via sequential diazotization–diazo coupling of aromatic amines with coupling agents at room temperature in the presence of BF3.SiO2 as acidic catalyst. The obtained aryl diazonium salts bearing silica supported boron tri-flouride counter ion was sufficiently stable to be kept at room temperature in the dry state.