Alcohols have acidic character as the react with active
metals like sodium or potassium liberating hydrogen. For example,
C2H5OH + Na → C2H5ONa
+ ½H2
However, alcohols are weak acids. This is because they
have an electron-releasing alkyl group (+I effect) which increases electron
density around oxygen so that the release of a proton is rendered difficult.
Acidic character of alcohols shows the following order:
primary alcohol > secondary alcohol > tertiary
alcohol
The acidic character of alcohols depends on the release
of H+
from O–H. The +I effect increases from
primary alcohols (having one alkyl group) to secondary alcohols (having two
alkyl groups) to tertiary alcohols (having three alkyl groups).
As a result, in tertiary alcohols, the release of a
proton is most hindered making them the weakest acids of the three classes of
alcohols.
In the gas phase, order of acidity is the exact opposite
of that given above.
Currently, this ought to be beyond the scope of the CAPE syllabus.
