JEE Main 2022 · 25 Jul · Shift 1 · Chemistry Q74

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ChemistrySingle correct+4 / -1Question 74 of 90

Most stable product of the following reaction is :

3-Methylpentan-2-ol with OH on a wedge at C2 and the ethyl on a wedge at C3, treated with (i) p-toluenesulfonyl chloride, pyridine, (ii) NaCN, DMF.

CN on a wedge, ethyl on a wedge

2,3-Dimethylpentanenitrile drawn with CN on a wedge at C2 and the ethyl on a wedge at C3 (same zigzag as the starting alcohol).

CN on a wedge, ethyl on a hash

2,3-Dimethylpentanenitrile drawn mirrored, with CN on a wedge at C2 and the ethyl on a hashed bond at C3.

CN on a wedge, ethyl on a wedge (drawn mirror image)

2,3-Dimethylpentanenitrile drawn mirrored, with CN on a wedge at C2 and the ethyl on a wedge at C3.

CN on a hash, ethyl on a hash

2,3-Dimethylpentanenitrile with CN on a hashed bond at C2 and the ethyl on a hashed bond at C3.

Answer and worked solution

Official answer: B

Steps. Tosylation keeps the configuration at C2; $\mathrm{CN^-}$ then displaces OTs by $\mathrm{S_N2}$ with inversion at C2, C3 unchanged: option B.

(B)

Topics:SN1 and SN2 Optical isomerism and chirality

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JEE Main 2022 · 25 Jul · Shift 1, Chemistry question 74