Brønsted acidity of ceric ammonium nitrate in anhydrous DMF. The role of salt and solvent in sucrose cleavage

The generation of an unexpected Brønsted acidity in anhydrous DMF at 50 °C was evidenced by NMR measurements during the investigation on the course of sucrose cleavage by ceric ammonium nitrate (CAN). The formation of a nitrooxy derivative of DMF by reaction with CAN is responsible for this acidity. The reactivity of CAN at 50 °C with several solvents was evaluated by voltammetric and potentiometric measurements. The possible release of protons from these reactions, particularly when aqueous solvent mixtures are used, should always be taken into account in the mechanistic interpretation of CAN synthetic applications.