Prototropic tautomerism of tri- and tetra-phenyl-2,3(2,5)-dihydro-1,3,5-triazines

Abstract

Spectroscopic studies (i.r., u.v., and ¹H n.m.r.) of 2,2,4,6-tetraphenyldihydro-1,3,5-triazine (1), and other simple tri- and tetra-phenyldihydro-1,3,5,-triazines showed that (1), 2,4,6-triphenyldihydro-1,3,5-triazine (6), and its 2-methyl-(7). and 2-ethyl-(8) derivatives exist in an equilibrium mixture of 2,3-dihydro (a) and 2,5-dihydro (b) forms. From the ratio obtained from the spectra the 2,3-dihydro-(a) form was preferred in (1) and (6)–(8) in solution and in the solid state.