NA (nucleophilic addition) reaction of alcohols with aldehydes gives hemiacetal, whereas phenols react with aldehydes and ketones in acidic medium and give electrophilic substitution product (I)
, which further reacts with phenol to give (II) , Explain.

Explanation

Alcohols are reatively weaker nucleophiles and they add slowly to the group under neutral conditions. But in acidic medium, the rate increases due to the protonation of group and thereby increases the positive charge on carbonyl C atom, making it more reactive. In basic medium, `RO^(-)` is in equilibrium with `O^(-)H` and reacts more rapidly with the group than ROH. Morever, `RO^(-)` is a strong nucleophile.
i. In acidic medium:

ii. In basic medium:

With phenols, hemiacetal (PhOCH) (OH) R) is formed reversibily, which decomposes to PhOH and RCHO.

iii. Due to the resonance in phenol, the positivite charge at o-and p-positions makes it more reactive for electronphile to react and gives electrophile substitution product mainly at the para position.
iv. Reaction of acteone with phenol in acidic medium is as follows: