Alcohols as acids

0 Alcohols have acidities similar to that of water. 

Methanol is a slightly stronger acid than water (pATg = 15.7) but most alcohols are somewhat weaker acids. Values of pA a for several alcohols are listed in Table 11.3. 

Water and alcohols are the strongest acids in this series. 

0 StericaUy hindered alcohols such as tcrt-butyl alcohol are less acidic, and hence their conjugate bases more basic, than unhindered alcohols such as ethanol or methanol. 

One reason for this difference in acidity has to do with the effect of solvation. With an unhindered alcohol, water molecules can easily surround, solvate, and hence stabilize the alkoxide anion that would form by loss of the alcohol proton to a base. As a consequence of this stabilization, formation of the alcohol s conjugate base is easier, and therefore its acidity is increased. If the R group of the alcohol is bulky, solvation of the alkoxide anion is hindered. Stabilization of the conjugate base is not as effective, and consequently the hindered alcohol is a weaker acid. Another reason that hindered alcohols are less acidic has to do with the inductive electron-donating effect of alkyl groups. The alkyl groups of a hindered alcohol donate electron density, making formation of an alkoxide anion more difficult than with a less hindered alcohol. 

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The equations above showed the behavior of alcohols as acids. In the presence of strong acids, alcohols can also behave as bases ... 

As already mentioned, the main focus of this chapter is on the synthesis, structure, and reactivity of alkoxysilanes (silicic acid esters) and metal alkoxides (salts of alcohols as acids). 

The most active metals react with alcohols as acids and produce metal alkoxides together with hydrogen gas as by-products ... 

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