Tert-Butyl alcohol solvation

The lesser acidity of sterically hindered alcohols such as tert-butyl alcohol arises from solvation effects. 

The effect of alkyl substitution on alcohol acidity is due primarily to solvation of the alkoxide ion that results from dissociation. The more easily the alkoxide ion is solvated by water, the more stable it is, the more its formation is energetically favored, and the greater the acidity of the parent alcohol. For example, the oxygen atom of an unhindered alkoxide ion, such as that from methanol, is sterically accessible and is easily solvated by water. The oxygen atom of a hindered alkoxide ion, however, such as that from tert-butyl alcohol, is less easily solvated and is therefore less stabilized. 

Tert-butyl alcohol (TBA) is the largest monohydric alcohol fully solvated in water. A level of micro-heterogeneity and mixing in water-TBA systems is under debate [42-43]. EFP reliably predicts strengths of hydrogen bonding in various water-TBA dimers, as compared to the MP2/6-311-I— -G(d,p) calculations [35] (see Fig. 5.3). Intermolecular distances obtained by the EFP and MP2 methods differ by less than 0.1 A. Stabilities of the dimers by EFP are within 0.8 kcal/mol of the MP2 stabilities, with the largest error observed for the first (W-TBAa) water-TBA dimer. 

As shown in Figure 2, the rate of SAN copolymerization in the presence of ZnCl2 is solvent dependent. The greatest rates of polymerization were noted in 1-pentanol (solubility parameter 6=10.9 H) and tert.-butyl alcohol (6=10.6 H). The rates were correspondingly slower in less polar 1-octanol (6=10.3 H), and in more polar 1-butanol (6=11.4 H) and 1-propanol (6=11.9 H). PSAN swells slightly in 1-octanol, but is insoluble in the other alcohols. Presumably the optimum solubility parameter range 10.6-10.9 H (the solubility parameters of 1-pentanol and tert.-butyl alcohol) corresponds to the optimum solvency of the CTC and the optimum minimum solvation of the copolymer. The slower rates in 1-butanol and 1-propanol, both poor solvents for the copolymer, are probably due to the inability of the polarized CTC to penetrate the non-polar macroradical coil. The slower rate of... 

As was mentioned in section 2.3.3, ytterbium metal dissolves in liquid ammonia to yield ammoniated electrons and Yb " ions. This solution was used by White et al. (1978) to perform reductions of various aromatic systems, similar to the Birch reactions which use lithium or sodium as the metal. The addition of benzoic acid or anisole dissolved in a 10 1 mixture of THF-tert-butyl alcohol, to an ytterbium-ammonia solution gives 1,4-dihydrobenzoic acid (56% yield). Triple bonds are cleanly reduced to trans olefins (i.e. PhC CPh traK5-PhCH=CHPh 75%). The C=C double bonds of conjugated ketones are also reduced by this system. Since the reaction medium initially contains both solvated electrons and Yb + ions it is likely that the above reactions are not directly connected with the presence of divalent ytterbium species. 

At C(2) we apparently see "steric, approach control and product development control in direct conflict, for although the axial 2 -alcohol (12) is the predominant product when sodium borohydride is used in a polar solvent preference almost disappears when the reagent is lithium aluminium hydride in ether [12]. The anion in the latter reagent is effectively quite small because of the weak anion-solvating power of ether, so the "steric approach factor is small compared with the much more heavily solvated borohydride ion in a hydroxylic solvent. Even the sterically unhindered 3-ketones, and simple analogues like q-tert-butyl cyclohexanone [47], give the equatorial alcohols in greater... 

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