FT-IR STUDY OF THE PROTON POLARIZABILITY OF HYDROGEN-BONDS AND OF THEHYDROGEN-BONDED SYSTEMS IN A DI-MANNICH BASE OF 5,5'-DIMETHOXY-2,2'-BIPHENOL

The mono- as well as the di-Mannich bases of 5,5'-dimethoxy-2,2'-biphe nol are studied by FT-IR spectroscopy. It is shown that in these bases the protons remain localized at the phenol (C) atom. This result is i n contrast to those obtained earlier for more acidic biphenols in whic h the protons are not localized but fluctuate and the relevant hydroge n bonds show large polarizability. An intense infrared continuum in th e FT-IR spectrum of the mono-protonated di-Mannich base of 5,5'-dimeth oxy-2,2'-biphenol demonstrates that the intramolecular hydrogen bond i n this compound shows large proton polarizability. (C) 1998 Elsevier S cience B.V. All rights reserved.