UV SPECTROSCOPIC STUDY OF THE ACID-BASE REACTIONS OF 3-HYDROXYPYRIDINES AND 5-HYDROXYPYRIMIDINES

Article abstract of DOI:10.1007/BF00479612

The acid-base equilibrium behavior of alkyl(phenyl)-substituted 3-hydroxypyridines and 5-hydroxypyrimidines, and their dependence on pH values in aqueous solution, on the solvent, and on the phase composition, have been studied using UV spectroscopy.It has been found that in neutral aqueous solution all of the substituted 3-hydroxypyridines examined contain, in addition to the neutral form, a bipolar form, whose concentration depends on the nature and position of the substituent.In contrast, methyl substituted 5-hydroxypyrimidines form significant amounts of the bipolar form only in more acidic media.