Study of intermolecular interactions of aldehydes with trialkylphosphine oxides from absorption spectra in the infrared region

Abstract

The H-bonds of aldehydes (acetaldehyde and its mono-, di-, and trichloro derivatives) acting as proton donors in solutions and in carbon tetrachloride were studied by IR absorption spectroscopy. Triethylphosphine oxide, one of the strongest acceptors, was used as the proton, acceptor. The investigations were carried out in the frequency region of v(C-H) of aldehydes and v(P=0) of phosphine oxide. It was found that changes in the spectra corresponding to an H-bond formation are observed only in the case of chlorine derivatives of acetaldehyde, and they are most evident in the case of chloral. This corresponds to the increase in the protonation of the C-H group hydrogen by the action of a constantly increasing inductive effect with increase in the degree of chlorine substitution. It was shown that a characteristic feature of the H-bond with the participation of the aldehydes studied is the appearance of a doublet in the v(CH) region with a ∼100 cm-1 splitting having Fermi resonance nature.