Mise en évidence des tautomères énoliques des hydroxypyridines dans la source du spectromètre de masse

Abstract

3- and 4-Hydroxypyridines exist in their enolic form, in the gas phase, as evidenced by the similarity of the deuterium isotope effects on the loss of CO, calculated on nearly equimolar mixtures of HO- and DO-pyridines. This is confirmed by analysis of metastable ratios evaluated on hydroxypyridine fragment ions and on the same ions produced by direct ionization. 2-Hydroxypyridine shows a weaker isotope effect for the same reaction and this is confirmed by the study of an equimolar mixture of 2-ethoxy- and 2-ethoxy-d5-pyridines. It is shown that 2-hydroxypyridine also exists as its enolic form, in the gas phase.