Synthesis of oxalate from carbon monoxide and carbon dioxide in the presence of caesium carbonate

Abstract

In the presence of caesium carbonate, the direct reaction of CO₂ (110 atm) with CO (50 atm) resulted in reductive capture of CO₂ to give caesium oxalate in good yield (90.1%) at high temperature (380 °C). The reaction is characteristic of caesium carbonate. When lithium, sodium, potassium and rubidium carbonates were used, oxalate was scarcely produced. The effects of the reaction variables, such as the pressures of CO₂ and CO, and the reaction temperature, were examined to optimize the process. From the results of mechanistic studies including a separately examined two-step reaction, ¹³C-labelling experiments and IR spectroscopic studies of the intermediates, it was concluded that the reaction proceeds through a nucleophilic addition of CO upon the carbonyl carbon of CO₂ which is activated by the complexation to caesium carbonate.