POLAROGRAPHIC AND POTENTIOSTATIC REDUCTION OF CARBODIIMIDES: A MECHANISTIC STUDY

The polarographic reduction of aromatic carbodiimides in anhydrous aprotic solvents goes through a carbene intermediate by a diffusion controlled process in two one-electron steps. The first step is the rate-determining step and converts the carbodiirnide to a radical anion (6) that reduces further by a fast one-electron step to a carbene dianion intermediate (7). This abstracts an oxygen, along with protons, from the solvent to give diphenyl urea (9) or reduces further to methylene dianiline (12) .