Confirmation of the structure of the bicyclic oxidation product of dehydroascorbic acid bis‐phenylhydrazone

The structure of the bicyclic oxidation product of dehydro L‐ascorbic acid has been confirmed by detailed mass spectroscopy and 13C nmr spectroscopy as 3. This structure was put in doubt, when electron ionization mass spectroscopy detected a molecular peak two mass units higher than expected. Careful experiments at low temperature revealed that the molecular ion disproportionates when heated, giving ion 2 or one of its isomers