Temperature Dependence of the Dipole Moment of Mannich Bases with An Intramolecular Hydrogen Bond

Abstract

The dipole moments of Mannich bases with an intramolecular hydrogen bond have been measured as function of temperature. For two compounds where proton transfer is apparent in benzene from UV-VIS spectra, a distinct decrease of dipole moment with increasing temperature has been observed. The dipole moments and their temperature dependence have been analyzed in terms of a tautomeric equilibrium related to the proton transfer within the bridge. It is shown that the quantitative description of the proton transfer process obtained by UVspectroscopy is completely valid in the interpretation of the dielectric behavior.

Competitive intra- and intermolecular interactions in secondary Mannich bases

“…The dipole moments of these intramolecular hydrogen bonds were studied as a function of solvent polarity [5] and temperature [6], also providing evidence of proton transfer.…”