Solvent-free synthesis of substituted ureas from CO2 and amines with a functional ionic liquid as the catalyst

The synthesis of disubstituted ureas from amines and CO2 were carried out using a basic ionic liquid (IL) 1-n-butyl-3-methyl imidazolium hydroxide ([Bmim] OH) as the catalyst. The effects of reaction time, amount of [Bmim] OH, reaction temperature, pressure, and solvent on yields of the products were investigated. The results indicated that aliphatic amines, cyclohexylamine, and benzylamine could be converted to the corresponding ureas selectively in moderate yields under solvent-free conditions without using any dehydrating regent. The IL could be reused after a simple separation procedure.