Q. 144.1( 20 Votes )
Give two reaction
The acidic nature of phenol can be represented by the following two reactions:-
(a) Phenols react with sodium to give sodium phenoxide, liberating H2.
(b) Phenols react with sodium hydroxide to give sodium phenoxide and water as a by-product.
The acidity of phenol is more than that of ethanol. This is because phenol after losing a proton becomes phenoxide ion which undergoes resonance and is stabilized whereas ethoxide ion does not.
The resonating structures of phenoxide ion are shown as below:
The lone pair of electrons on oxygen delocalizes into the benzene (mesomeric effect) which reduces the electron density in the O-H bond. The O-H bonds are weaker and therefore breaks easily whereas in ethanol the electron releasing inductive effect of the alkyl group increases the electron density on the O-H bond. This strengthens the bond so the bond does not break easily. Therefore making ethanol less acidic than phenol.
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