A new way to make oxalic acid from CO2 and alkali formates: Using the active carbonite intermediate

Conversion of CO2 to valuable chemicals such as polymers via the electrochemical reduction formate followed by oxalate coupling reaction (FOCR) is an interesting concept replace fossil feedstocks with renewable ones. Yet, activation challenging and energy-intensive today production one molecule first requires two molecules. Recently we confirmed crucial role reactive carbonite intermediate in FOCR. Due its high reactivity, this might also be a strong enough nucleophile react directly. If case, can form directly from avoid need for double production. In work, successfully established conversion (with theoretical yield 52%) (via carbonite), well carbonate. The direct was dominant pathway incorporation oxalate. For enhancing oxalate, found temperature 200°C, stoichiometric amounts base, presence supercritical state most suitable. residence time strongly depending on reactor type but should kept minimum carbonate formation. hydride appeared cause formation carbonates side-product. increased higher temperatures longer times, which suggests consecutive decomposition formed reaction.