Mid- and near-IR study of the hydrogen bond interaction between N-methyldiacetamide and phenols

Abstract

The hydrogen bond complexes between phenol derivatives (p K a = 10.20−8.20) and N-methyldiacetamide (NMD) are studied by mid- and near-IR spectroscopy in carbon tetrachloride solution. The equilibrium constants and enthalpies of complex formation are determined and the results suggest that the proton acceptor ability of NMD is lower than that of monocarbonyl bases. Complex formation results in decoupling of the ν(CO) vibration. The frequencies and intensities of the bonded ν(OH) vibration are determined for the fundamental and first overtone transition. Hydrogen bond formation results in a very weak increase of the mechanical anharmonicity and a strong decrease of the intensity of the first overtone of the OH stretching vibration. The first ( μ 1) and second ( μ 2) dipole moment derivatives are calculated. In this limited domain, a linear correlation is found between Δμ 1 and Δμ 2, the increase of the dipole moment derivatives resulting from hydrogen bond formation.