Question

plzzzz explain- WHY PHENOXIDE ION IS MORE STABLE THAN PHENOL??

Answer 1

phenol and phenoxide ion both are stabilized by resonance. In case of phenol the lone pair on oxygen atom get delocalize over the ring and if we look into the resonance structures of phenol there is a charge seperation i.e. there is positive charge on oxygen atom and negative charge on the ring carbons. This type of resonance structures have small contributions to the hybrid in stabilizing the compound. Whereas in case of phenoxide ion, the negative charge on the oxygen atom get delocalize and no such charge separation take place. Therefore the resonance structures of phenoxide ion has more contributions toward the hybrid in stabilising the phenoxide ion. Hence phenoxide ion is more stable than phenol.

Answer 2

Answer:

The phenoxide ion is a WEAKER base than alkoxide ion, because the phenoxide ion is resonance stabilized, and requires less solvation.

Explanation:

The pKa of phenol, C6H5OH = 9.95 in water. This makes phenol a MUCH stronger acid than comparable secondary alcohols, the which, if soluble in water, would undergo no acid base behaviour.

The charge density of the phenoxide anion is much less than the comparable aliphatic alkoxide, because the charge is delocalized around the ring to some extent. On the other hand, the charge on alkoxide is localized to the oxygen centre. Phenoxide, thus causes less solvent ORDER upon deprotonation, and its acidity is entropically favoured. This is thus an entropy rather than a enthalpy phenomenon.