Question
Write a note on acidity of alcohols.
✓
Answer
→ Acidity of alcohols: The acidic character of alcohols is due to the polar nature of O-H bond. An electron-releasing group (-CH3, C2H5) 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 :
→ Alcohols are, however, weaker acids than water. This can be illustrated by the reaction of water with an alkoxide.
→ 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).
→ 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.
→ Alcohols are, however, weaker acids than water. This can be illustrated by the reaction of water with an alkoxide.
→ 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).
→ 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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