Polymer/HIO4: An efficient catalyst for solvent-free synthesis of 2-naphthol azo dyes

A convenient, one-pot method for the synthesis of diazonium salt has been developed by the sequential diazotization of aromatic amines with NaNO2, polymer- supported periodic acid (PPIA) and 2-naphthole under solvent-free conditions at room temperature. By using this method, several types of aromatic amine, containing electron-withdrawing and electron-donating groups, were rapidly converted to the corresponding azo dyes in good to excellent yields. The ensuing aryl diazonium salts supported on polymer (aryl diazonium polymer), ArN2+IO4- were sufficiently stable to be kept at room temperature in the dry state. The use of mild reaction conditions and an inexpensive procedure are further advantages of this method.