Question

a) Write the mechanism of acid catalysed dehydration of ethanol to ethene.
b) Between phenol and alcohol which is more acidic? Why?

Answer 1

a. (Ref. image)

b. Phenol is more acidic than alcohol, because phenoxide ion is resonance stabilized where as alkoxide is not resonance stabilized. In case of alkoxide ion, the negative charge is localised on O atom whereas in case of phenoxide ion, the negative charge is localised on benzene ring. Hence, phenoxide ion is more stable than alkoxide ion.

Note: In case of phenol, the resonance leads to charge separation. Hence, phenol is less stable than phenoxide ion.