Direct synthesis of salicylamide from phenol and urea over ZnO catalyst

An effective and facile route for direct synthesis of salicylamide was firstly developed via the reaction of phenol with urea over solid catalysts. Among the catalysts used, ZnO exhibited the best catalytic performance. Based on the characterization of ZnO before and after the reaction by means of XRD, ICP-AES and FTIR, the high performance of ZnO was closely related to the formation of a relatively stable Zn-complex. Furthermore, the influences of various conditions, such as reaction temperature and time, the molar ratio of phenol to urea and the amount of catalyst were investigated in detail.