Diarylformamides as a safe reservoir and room temperature source of ultra-pure CO for a 'green' rWGS reaction.

Diarylformamides are shown to be a safe reservoir and source of CO. Perfectly selective decarbonylation is achieved in solution at room temperature with potassium and cesium diarylamide catalysts. Moreover, solvent-free decarbonylations may be run either in a diphenylformamide melt at 70 ºC or, when the bisformamide 9 is used, in the solid state at 88 ºC in virtue of its improved atom economy. These These simple and practical transition-metal-free reactions afford ultra-pure (i.e. dry and solvent-free) CO at moderate temperatures and the byproduct diarylamines are recycled as pure compounds. In the absence of catalysts, diarylformamides 1 and 9 are long-term stable at > 200 ºC.  DFT-calculations indicate a reaction pathway with a rate-determining deprotonation of Ph2NC(O)H and a barrier-free CO elimination from Ph2NC(O)-.