Reactive collisions in quadrupole cells. 2. H/D exchange reactions of enolate ions with CH3od and C2H5OD

The H/D exchange reactions of enolate ions with CH₃OD and C₂H₅OD at low collision energies in the quadrupole collision cell of a hybrid tandem BEqQ mass spectrometer have been studied. The optimum parameters for exchange were elucidated using the enolate ion of acetone as a test reactant ion. With the exception of the enolate ions of 2,4-pentanedione and dimethylmalonate, all the enolate ions studied underwent exchange with CH₃OD and C₂H₅OD. Ion signals were observed corresponding to exchange of from one to all of the enolic hydrogen atoms. The H/D exchange reaction was more facile with C₂H₅OD as the reagent gas, and the results with this gas clearly permit a count of the number of enolic hydrogen atoms present in the molecule.