Solvent free synthesis of cyclic ureas and urethanes by carbonylation method in the basic dicationic ionic liquid catalysts

The direct synthesis of cyclic ureas and urethanes from dimethyl carbonate, diamines or amino alcohols is a tandem reaction that typically involves two steps including amino or hydroxyl proton abstraction and subsequent nucleophilic attack on carbonyl carbon of dimethyl carbonate by anions of basic ionic liquid. In this study, basic dicationic ionic liquids as the metal-free green versatile materials were demonstrated to be an efficient and recyclable bifunctional catalyst in the direct synthesis of ureas and urethanes. Remarkably, the excellent ethylenediamine conversion up to ∼90% and ∼91% cyclic ureas selectivity were achieved by −OH anionic ionic liquid as catalyst at ambient reaction conditions. Furthermore, the ambient reaction conditions, simple workup procedure, wide substrate scope and cost effectiveness are some of the other outstanding features of this protocol that make it economical and sustainable.