Spectral manifestation of interaction between hydroxyl groups of phenolic antioxidants and solvents

The spectral and structural characteristics of sterically hindered phenols in chlorinated and aromatic solvents are analyzed by IR spectroscopy. The spectral manifestations of hydrogen bonds of the hydroxyl groups of sterically hindered phenols in chlorinated and aromatic hydrocarbons are investigated. It is known that hydroxyl groups are not capable of forming intermolecular hydrogen bonds in phenols due to their shielding by bulky substituents. It is exactly this fact that has motivated their selection as additives inhibiting hydrocarbon oxidation. Nevertheless, an introduction of sterically hindered phenols into the hydrocarbon system may affect the established pattern of intermolecular interactions and change the phenol spectral characteristics. The intensities and peak positions in the absorption bands of solutions are shown to differ within the range 3700-3200 cm -1, depending on the solvent type and polarity, the concentrations of phenols being equal. The observed changes in the spectral characteristics are attributed to the intermolecular interactions between the phenol hydroxyl groups and solvents.