JEE Main 2022 · 26 Jun · Shift 1 · Chemistry Q75

← JEE Main 2022 · 26 Jun · Shift 1

ChemistrySingle correct+4 / -1Question 75 of 90

Consider the above reaction sequence and identify the product B.

BrMgCH2CH2MgBr + CH3COCH2COCH3 gives 'A', which with H2O gives the major product 'B'.

1,3-dimethylcyclopentane-1,3-diol

cyclohexane-1,4-diol

4,5-dimethylcyclopentane-1,3-diol

Cyclopentane ring with OH on two carbons (1,3) and CH3 on the two remaining adjacent carbons (4,5).

4,5-dimethylcyclopentane-1,3-dione

Answer and worked solution

Official answer: A

Double addition. $\mathrm{BrMgCH_2CH_2MgBr}$ adds to both C=O groups of acetylacetone, closing a five-membered ring: C2, C3 and C4 of the dione plus the two $\mathrm{CH_2}$ groups.

Hydrolysis gives B, 1,3-dimethylcyclopentane-1,3-diol.

(A)

Topics:Alcohols Nucleophilic addition

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JEE Main 2022 · 26 Jun · Shift 1, Chemistry question 75