Heterogeneous synthesis of dimethylhexane-1,6-dicarbamate from 1,6-hexanediamine and methyl carbonate in methanol over a CeO2 catalyst

Abstract The efficient synthesis of dimethylhexane-1,6-dicarbamate (HDC) from 1,6-hexanediamine (HDA) and methyl carbonate over a series of heterogeneous catalysts ( e.g. , MgO, Fe 2 O 3 , Mo 2 O 3 , and CeO 2 ) was investigated. The reaction pathway was confirmed as an alcoholysis reaction through a series of designed experiments. Under optimized conditions, 100% HDA conversion with 83.1% HDC total and 16.9% polyurea was obtained using a one-step with high temperature procedure with CeO 2 as the catalyst. A new two-step with variable temperature technology was developed based on the reaction pathway to reduce the polyurea yield. Using the proposed method, the HDC total yield reached 95.2%, whereas the polyurea yield decreased to 4.8%. The CeO 2 catalyst showed high stability and did not exhibit any observable decrease in the HDC yield or any structural changes after four recycling periods.