On the association of aminopyridines

Dielectric, IR and vapor pressure studies were performed on solutions of 2- and 3-aminopyridines and their methylderivatives. Ab initio calculations w ere also carried out using the DFT-B32LYP method at the 6-31G** level. In a ll cases, an increase of the effective dipole moment with increasing concen tration is observed in contradiction to what is assumed in literature and n on-polar cyclic dimers of 2-aminopyridine are found in the solid state. The results obtained in this paper seem to show that in solution, polar dimers are formed with the participation of NH2 groups as proton accepters. (C) 2 000 Elsevier Science B.V. All rights reserved.