Question
Write a note on acidity of alcohols.
✓
Answer
$\rightarrow$ Acidity of alcohols: The acidic character of alcohols is due to the polar nature of $O-H$ bond. An electron$-$releasing group $\ce{(-CH_3, C_2H_5) 2}$ increases electron density on oxygen tending to decrease the polarity of $O-H$ bond. This decreases the acid strength. For this reason, the acid strength of alcohols decreases in the following order :
$\rightarrow $ Alcohols are, however, weaker acids than water. This can be illustrated by the reaction of water with an alkoxide.
$\rightarrow$ This reaction shows that water is a better proton donor $($i.e., stronger acid$)$ than alcohol. Also, in the above reaction, we note that an alkoxide ion is a better proton acceptor than hydroxide ion, which suggests that alkoxides are stronger bases $($sodium ethoxide is a stronger base than sodium hydroxide$).$
$\rightarrow$ Alcohols can act as both bronsted bases as well as acids. It is due to the presence of unshared electron pairs on oxygen. which makes them proton acceptors.
$\rightarrow $ Alcohols are, however, weaker acids than water. This can be illustrated by the reaction of water with an alkoxide.
$\rightarrow$ This reaction shows that water is a better proton donor $($i.e., stronger acid$)$ than alcohol. Also, in the above reaction, we note that an alkoxide ion is a better proton acceptor than hydroxide ion, which suggests that alkoxides are stronger bases $($sodium ethoxide is a stronger base than sodium hydroxide$).$
$\rightarrow$ Alcohols can act as both bronsted bases as well as acids. It is due to the presence of unshared electron pairs on oxygen. which makes them proton acceptors.
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