nano silica/ hio4 as a green and reusable catalyst for synthesis of 2-naphthol azo dyes under grinding conditions

nanosilica periodic acid (nano-spia) is found to be a new, powerful, and reusable heterogeneous catalyst for the rapid synthesis of 2-naphtholazo dyes via diazotization of aromatic amines and followsazo coupling with 2-naphthol under solvent-free conditions at room temperature by grinding. eco-friendly, heterogeneous reaction conditions, high stability of diazonium salt, simple experimental procedures, and high yields are some of the important advantages of this method.