Tautomerism and the spectroscopic properties of some 4,6-disubstituted pyrimedines

Tautomerism of some 4,6-disubstituted pyrimidines (with the electron-donor groups such as OH, SH and NH₂) is discussed with regard to their electronic absorption spectra. The spectra of different tautomeric forms of the molecules are satisfactorily interpreted by means of the Pariser—Parr—Pople type of calculations.