Solvent-free synthesis of melamines under microwave irradiation

A fast, highly efficient and environmentally friendly solvent-free procedure under microwave irradiation, using silica gel supported reagents, for the synthesis of melamines, including ones with a broad range of biological activities, is developed. The main advantages of the synthetic approach presented here are the cheap and easily available starting material, cyanuric chloride, and the considerable rate enhancement in comparison with a thermal reaction. The scope of the reaction, towards the amine used, is also studied and it is shown that the method is valid as a highly effective one when moderately bulk amines are used. The by-product of the reaction, hydrogen chloride, is quenched as ammonium salts, preventing its release into the environment.