THE INFRARED FREQUENCIES AND INTENSITIES OF THE HYDROXYL GROUP IN 2,6-DI-tert-BUTYL-4-SUBSTITUTED PHENOLS

The infrared frequencies, intensities, and apparent half band widths of the O—H stretching band of a series of 2,6-di-tert-butyl-4-substituted phenols have been measured in carbon tetrachloride solution and compared with the corresponding 4-substituted phenols. The frequencies of the former are 36 cm−1 higher than the latter and the intensities are also slightly higher. Both the frequency and intensity follow a Hammett ρσ relation. It is shown that the O—H bond lies in the plane of the benzene ring, the increase in frequency and intensity being ascribed to a steric repulsion of the phenolic hydrogen by the adjacent tert-butyl group.