A green, efficient reductive N-formylation of nitro compounds catalyzed by metal-free graphitic carbon nitride supported on activated carbon

Metal-free graphitic carbon nitride supported on activated carbon was fabricated via a simple pyrolysis for onepot reductive N-formylation of nitro compounds with formic acid and sodium formate was employed as promoter. Under the conditions, this transformation was successfully achieved without any solvent. The support activated carbon and pyrolysis atmosphere had important influence on catalytic behavior of catalyst. SEM, TEM, XRD, XPS, EPR, FT-IR, Raman spectrum and N2 adsorption/desorption characterizations revealed that air pyrolysis enabled g-C3N4 to generate more carbon defects and the support AC effectively dispersed g-C3N4 to expose more active sites. Using our procedure, a broad set of nitro compounds was converted to their corresponding formamides with various functional group tolerances. The catalyst could be recycled several times without marked loss of activity. In short, we provided an efficient and sustainable protocol for the expedient synthesis of formamides from nitro compounds.