Here we report the observation that, depending on the solvent used for the electrospray, 2-nitrophloroglucinol undergoes a deprotonation from different sites forming two tautomeric gas phase ions. Those ions differ by the collision-induced dissociation (CID) spectra and by the gas phase hydrogen/deuterium (H/D) exchange kinetic. We performed H/D exchange in the electrospray ionization (ESI) source by saturation ESI region with vapors of deuterated solvent (D2O). It was observed that [2- nitrophloroglucinol-H]- exchanges two -OH hydrogens when MeOD is used as the spray solvent but when the spray solvent is 50:50 MeOD/D2O we observed an additional two H/D exchanges at the aromatic ring. We propose that the reaction occurs via a keto-enol tautomerization mechanism which was found to be energetically favorable.
- FT ICR
- Hydrogen/deuterium exchange