CH3COONa as an effective catalyst for methoxycarbonylation of 1,6-hexanediamine by dimethyl carbonate to dimethylhexane-1,6-dicarbamate

Methoxycarbonylation of 1,6-hexanediamine (HDA) by dimethyl carbonate (DMC) was carried out, using, for the first time, CH3COONa as catalyst. The effects of the solvent, reaction temperature, reaction time, and catalyst amount, were investigated. A yield as high as 99.0% of dimethylhexane-1,6-dicarbamate 2 has been obtained at a temperature of 348 K and a reaction time of 6 h. Mechanistic studies revealed that N-substituted acetamide, as the active intermediate product, and NaOH were first formed via the reaction between HDA and CH3COONa. A further reaction between the N-substituted acetamide and DMC generated carbamates and methyl acetate, via a hexatomic ring intermediate. The CH3COONa catalyst was finally recovered through the reaction between NaOH and methyl acetate, which thus completed the catalytic cycle.