Efficient Method of Synthesis of N,N′-Disubstituted Ureas/Thioureas by a Zinc Chloride Catalyzed Thermal Reaction

Abstract

Symmetrically N,N′-disubstituted ureas/thioureas were synthesized by heating amines or phenyl hydrazine and urea/thiourea on a preheated hot plate at 80–85°C under solvent-free conditions in the presence of a catalytic amount of ZnCl₂ as a catalyst. The protocol has the advantages of not using toxic phosgene and other hazardous substrates or organic solvents. Increased reaction rate, good yield, and a simple workup procedure are involved.

Keywords:

• Disubstituted ureas/thioureas
• solvent-free reaction
• thermal condition
• ZnCl₂

Notes

^a All the products were characterized by spectral analysis and compared with authentic samples.

^b Isolated yields.

^c Melting points of compounds are consistent with reported values.

^a All the products were characterized by spectral analysis and compared with authentic samples.

^b Isolated yields.

^c Melting points of compounds are consistent with reported values.