JEE MAIN - Chemistry (2025 - 29th January Evening Shift - No. 10)
Which one of the following, with HBr will give a phenol?
_29th_January_Evening_Shift_en_10_1.png)
_29th_January_Evening_Shift_en_10_2.png)
_29th_January_Evening_Shift_en_10_3.png)
_29th_January_Evening_Shift_en_10_4.png)
Explanation
Relation with HBr to give phenol
(1) _29th_January_Evening_Shift_en_10_5.png)
The reaction involves two steps,
$\star$) The lone pair of oxygen atom attacks on the hydrogen of HBr.
$\star$) The nucleophile Br$^-$ attacks on the methyl group which lead to the formation of phenol along with methyl bromide.
Phenol is formed from this compound on reaction with HBr.
(2) _29th_January_Evening_Shift_en_10_6.png)
No phenol formation in this case because alkyl chain is attached to the benzene ring and on addition of H-Br, either H$^+$ or Br$^-$ get attached to this chain and no $-$OH group is formed as it is directly bonded to the benzene ring.
(3) _29th_January_Evening_Shift_en_10_7.png)
No phenol formation in this case. $-$OH group is formed as
_29th_January_Evening_Shift_en_10_8.png)
So, phenol product is formed in case of option (1) compound only.
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