An Environmentally Benign Method for the Synthesis of SymmetricalN, N′-Disubstituted Thioureas in a Water Medium

An environmentally benign method for the synthesis of symmetrical N, N′-disubstituted thioureas in a water medium using poly(ethylene glycol)-400 (PEG-400) as a catalyst and a microwave as a heating source is described. Diaryl- and dialkyl-thioureas efficiently are synthesized by the reactions of thiourea with a variety of amines. This protocol has advantages of (a) no use of hazardous reagents and volatile organic solvents, (b) a rapid reaction rate, (c) a high yield, and (d) a simple work-up procedure.