JEE Main 2022 · 24 Jun · Shift 1 · Chemistry Q76

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ChemistrySingle correct+4 / -1Question 76 of 90

4-Methoxybenzyl bromide (structure shown) is treated with (i) NaCN (ii) $\mathrm{OH^-}$ (iii) Cyclohexanone (iv) $\mathrm{H_2}$ , Ni, to give A, the major product.

The major product of the above reactions is :

4-Methoxybenzyl bromide reacting with (i) NaCN (ii) OH⁻ (iii) cyclohexanone (iv) H2, Ni to give A, the major product.

Structure (A) shown

2-cyclohexyl-2-(4-methoxyphenyl)ethan-1-amine

Structure (B) shown

1-[amino(4-methoxyphenyl)methyl]cyclohexan-1-ol

Structure (C) shown

2-cyclohexyl-2-(4-methoxyphenyl)acetamide

Structure (D) shown

1-[2-amino-1-(4-methoxyphenyl)ethyl]cyclohexan-1-ol

Answer and worked solution

Official answer: D

(i) NaCN. $S_N2$ substitution: $\mathrm{ArCH_2Br\rightarrow ArCH_2CN}$ (Ar = 4-methoxyphenyl).

(ii) $\mathrm{OH^-}$ . The benzylic H next to CN is acidic; base forms the carbanion $\mathrm{Ar\bar CHCN}$ .

(iii) Cyclohexanone. The carbanion adds to the C=O: $\mathrm{ArCH(CN)\text{-}C(OH)}$ of the cyclohexane ring.

(iv) $\mathrm{H_2}$ , Ni. The nitrile is reduced to $\mathrm{CH_2NH_2}$ .

Product. 1-[2-amino-1-(4-methoxyphenyl)ethyl]cyclohexan-1-ol, structure D.

(D)

Topics:Cyanides and isocyanides Nucleophilic addition Amines

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JEE Main 2022 · 24 Jun · Shift 1, Chemistry question 76