Hydrogen bonding of the hindered phenols, 2-lsopropylphenol, 2,6-di-isopxopylphenol, 2-1-butylphenol, 2-methyl-6-t-butylphenol, and 2,6-di-t-butylphenol, has been studied by observing the chemical shifts of -OH group protons* Boon temperature dilution shifts In carbon tetrachloride of the phenolic -OH gives dimerization constants K of 1.7, 1.3, 1.0, £ 0.05, and £ 0.0$, respectively, for the five phenols. Association constants % for phenol-dioxane complexes were obtained from the phenolic -OH dilution shifts in l,4 dioxane, employing general algebraic expressions derived for the purpose. The K-'s are in the same sequence as the Kgs but about ten-fold larger, consistent .with the greater ease with which a smaller molecule approaches the phenolic. -0&-. Observations of both the ethanolic and the phenolic -OH dilution shifts in ethanol-phenol solutions gave similar results, which were limited to a qual¬itative interpretation by the relatively strong polymerization of the ethanol.
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