Question

3-tert-butylphenol reacts with different halogens by electrophillic substitution under appropriate conditions that are given below:

The observed pattern of electrophillic substitution can be explained by

• (A) the steric effect of halogen
• (B) the steric effect of tert-butyl group
• (C) the electronic effect of the phenolic group
• (D) the electronic effect of the tert-butyl group

Answer 1

The Correct Option is A, C, D

Explanation:
Chloronium ion is least bulky and a tri-substituted product is obtained.(I)

Mono substituted product is obtained on iodination because of stearichindrence of the $1^{+}$ ion as well as the tertiary butyl group. The hydrogenat the least hindered site, ortho to the -OH group is substituted.(ii)

${\mathrm{Br}}^{+}$ ion is less bulky and substitution takes place at both ortho and para positions.(iii)

Chloronium ion is least bulky and a tri-substituted product is obtained.

Answer 2

Ans: This is because of 

• The steric effect of halogen
• The electronic effect of the phenolic group 
• The Electronic effect of the tert-butyl group 

The steric effect of halogen is the size and the bulkiness of the halogen group, which can affect the reactivity of the reaction. This is because of the spatial arrangement of the molecules that can hinder the chemical reaction. 

The phenolic group is the one with  an OH group attached to the aromatic compound. This effect is due to the electronegativity of the oxygen atom and also the withdrawing effect of the electron density through resonance and the inductive effect. 

The tert group is the substituent that is common. It has three methyl groups to the carbon atom. This effect is due to the steric hindrance and the inductive effects.