A new route of CO2 catalytic activation: syntheses of N-substituted carbamates from dialkyl carbonates and polyureas

This paper reports an effective route for the syntheses of N-substituted dicarbamates from dialkyl carbonates and polyurea derivatives, in which polyurea derivatives could be successfully synthesized from aliphatic diamines and CO2 in the absence of any catalyst. Under the optimized reaction conditions, various N-substituted carbamates were successfully synthesized with 93–98% isolated yields over a MgO–ZnO catalyst. The catalyst could be reused for several runs without deactivation. The catalysts were characterized with X-ray photoelectron spectroscopy, X-ray diffraction and temperature-programmed desorption.