Unsymmetrical urea and thiourea derivatives: An efficient nano BF 3-SiO 2 catalyzed PEG-400 mediated sonochemical synthesis and biological evaluation

An efficient and green approach has been developed for the synthesis of (substituted phenyl)-3-(4-(4-nitrophenylthio)phenyl)urea/thiourea derivatives 6(a-j) using non-hazardous green solvent, PEG-400 under ultrasound irradiation conditions in the presence of a reusable silica-supported Lewis acid catalyst, nano-BF 3-SiO 2via simple addition reaction of 4-(4-nitrophenylthio)aniline (4) with substituted phenyl isocyanates/isothiocyanates 5 (a-j). The advantages of developed method are convenient, offered higher yield of products with purity, less reaction time, easy work-up and reusability of the catalyst. Structures of the title products were established by IR, NMR ( 1H, 13C), mass spectral data and elemental analysis. Antimicrobial activity of the newly synthesized compounds was tested and the bio-screening data disclosed that urea derivatives, 6a and 6d, and thiourea derivatives, 6f, 6i and 6j showed potential antimicrobial activity against the growth of selected microorganisms.