Synthesis of dialkyl hexamethylene-1,6-dicarbamate from 1,6-hexamethylenediamine and alkyl carbamate over FeCl3 as catalyst

A series of catalysts (e.g. FeCl3, Zn(OAc)2, Pb(NO3)2, etc.) were tested for the trans-esterification reaction of 1,6-hexamethylenediamine (HDA) with methyl carbamate (MC), ethyl carbamate (EC), and butyl carbamate (BC) to afford dialkyl hexamethylene-1,6-dicarbamate (AHDC). By applying the optimized condition, 100% conversion of HDA and 93% yield to diethyl hexamethylene-1,6-dicarbamate (EHDC) could be obtained using FeCl3 as catalyst. The desired products could be precipitated by adding water into the resulting mixture, and the activity of recovered catalyst could be maintained.