Synthesis and properties on some 2-, 4- and 5-aminopyrimidines. Effect of -NH2 and ortho-C methylation on protolytic equilibria and electronic absorption spectra.

A number of new 2-, 4- and 5-aminopyrimidines with sterical hindrance to the amino group rotation were synthesized. The pKa values and u.v. absorption spectra of the aminopyrimidines were measured in order to elucidate the conformation of the amino group depending on the place of substitution.