Synthesis Of di- and tri-substituted thiourea derivatives in water using choline chloride–urea catalyst

In this work, di- and tri-substituted thiourea derivatives have been synthesized via a one-pot, three-component reaction from carbon disulfide and aliphatic or aromatic amines using choline chloride-urea deep eutectic solvent as a catalyst in water. Both cyclic and acyclic thiourea derivatives with two or three substituents were synthesized successfully. The reactions were done at 25–100°C, using 5–20 mol% catalyst, in 3–5 h and the GC-Mass yields were between 60% and 95%. All products were characterized using FT-IR, ¹H-NMR, ¹³C-NMR, GC-MS and melting point analyses. The results showed that both water and the DES have important effects on the yield and the rate of this reaction and both of them are necessary to obtain higher yields in less time. The extra experiment, which was designed to study the mechanism of the reaction, showed that an isothiocyanate intermediate was formed in the reaction. Finally, the results showed that by the increase of the amine's nucleophilicity, the reaction occurs faster and gives higher yield.