Question

whay electrons do not move towards OH in phenol,even though OH group is more electron withdrawing group than phenyl?​

Answer 1

Explanation:

Aryl groups can be electron donating or electron withdrawing based on the type of substituent attached to the ring. If we consider just the phenyl group, it is electron withdrawing by induction(-I effect).This is pretty clear from the pKa values of acetic acid (pKa 4.75) and benzoic acid ( pKa 4.2).

Answer 2

Electrons do not move towards OH in phenol, even though OH group is more electron withdrawing group than phenyl. This can be explained as follows:

• When connected in alkyl chains, OH acts as a strong electron withdrawing group and tends to pull the electron density towards itself.
• However, in aryl rings like phenyl, it shows mesomeric effect and donates its lone pair to the aromatic ring.
• This is because the lone pair on the phenyl ring is delocalized and the electron density is shared by three carbon atoms. If the reverse happens, all the electron density will be localized on oxygen and will destabilize the system.
• Hence, for the overall stability of the molecule electrons do not move towards OH in phenol, even though OH group is more electron withdrawing group than phenyl.