Abstract: 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.

Syntheses of N-substituted dicarbamates from dialkyl carbonates and polyurea derivatives based on diamines and CO2.

Conclusions: In conclusion, an effective route for the syntheses of N-substituted carbamates from dialkyl carbonates and polyurea derivatives over MgO–ZnO catalyst was developed. The polyuria derivatives could be successfully synthesized from aliphatic diamines and CO₂ in the absence of any catalyst. Under the optimized reaction conditions, several important N-substituted carbamates were successfully synthesized with 93–98% isolated yields. The MgO–ZnO catalyst could be reused for several runs without deactivation. The characterization results of the catalysts suggested that the specific kinds and amounts of the basic sites might be the major reason for the highly catalytic activity of MgO–ZnO.