Abstract Hydration of 2-(2-hydroxyethyl) amino-6-methylpyrimidin-4 (3 H)-one forms an equilibrium mixture of 4-oxo-3, 4-dihydro and 4-hydroxy tautomers. The intermediate in mutual transitions of these tautomers has a zwitter ionic structure. The equilibrium shifts to the 4-oxo-3, 4-dihydro form as the polarity of the medium decreases.
[Schmedes Justus Liebigs Annalen der Chemie, 1925 , vol. 441, p. 199 Full Text Show Details Behrend; Haertel Justus Liebigs Annalen der Chemie, 1921 , vol. 422, p. 84]
