Fragmentation of collisionally activated hydroxyphenoxide anions in the gas phase

Low-energy collisionally activated dissociation of O-deprotonated dihydroxybenzenes (catechol, resorcinol, hydroquinone) in the gas phase causes both fragmentation to form C₆H₄O₂]^– ions by loss of the remaining oxygen-bound hydrogen atom and intramolecular hydrogen atom migration from O to C. The rearranged anions then undergo ring-cleavage reactions which are different in each case. Both catechol and hydroquinone produce fragments which are the result of the loss of two carbon atoms and both oxygen atoms but the proposed mechanisms are different. Resorcinol also produces a fragment which derives from the loss of carbon dioxide. For this process a mechanism is proposed which involves a 6-methylpyranone anion intermediate.