ИСТИНА

We developed an approach capable to perfom in ESI-source H/D exchange at non-labile C-H sites capable by an increase in desolvation temperature. It was found that heating the desolvation capillary up to 400C leads to the in-ionization source H/D exchange of some specific non-labile hydrogen atoms of hydroxybenzoic acids and aromatic amino acids. The data obtained are indicative of the tautomeric nature of the observed exchanges. The results proved the crucial role of the compound structure in H/D exchange at non-labile sites and revealed an influence of acceptor group (e.g. carboxyl) on reaction selectivity. This allowed us to conclude that negative ionization mode can be considered as an analogue of the base-catalyzed conditions in the liquid state and an increase in desolvation temperature shifts equilibrium between tautomeric forms.