Organic Compounds Containing Oxygen: Chemistry | JEE Main
Match List I with List II:
is reacted with reagents in List I to form products in List II.
Choose the correct answer from the options given below:
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Hint 1 of 3
What product is formed when cyclohex-2-en-1-one undergoes Clemmensen reduction with Zn(Hg)/conc. HCl (Reagent A)?
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Step-by-step solutionView
Correct answer
The correct matching is A-III, B-I, C-IV, D-II based on selective carbonyl reductions, double-bond reductions, and Clemmensen reduction.
Option analysis
Why each option works or fails
A · A-IV, B-III, C-II, D-I
Assuming that Clemmensen reduction (Zn(Hg)/HCl) reduces the alkene rather than fully reducing the carbonyl to a methylene group, or confusing Luche/DIBAL-H with complete reduction. Recognize that Zn(Hg)/conc. HCl reduces carbonyl groups to −CH2−, yielding cyclohexene from cyclohex-2-en-1-one (A-III).
B · A-I, B-III, C-IV, D-II
Confusing the reagents Zn(Hg)/conc. HCl and CeCl3⋅7H2O/NaBH4, leading to swapped assignments between cyclohexene and cyclohex-2-en-1-ol. Associate the Luche reagent (NaBH4+CeCl3) with selective 1,2-reduction of α,β-unsaturated ketones to allylic alcohols (B-I).
C · A-III, B-I, C-II, D-IV
Swapping the outcomes of H2/Pd and LiAlH4 reductions for α,β-unsaturated ketones. Recall that H2/Pd selectively reduces the conjugated alkene to give cyclohexanone (C-IV), whereas LiAlH4 reduces both the double bond and the carbonyl group to give cyclohexanol (D-II).
D · A-III, B-I, C-IV, D-II
Correct option: reflects accurate knowledge of selective reductions for α,β-unsaturated ketones. Zn(Hg)/conc. HCl gives cyclohexene (A-III); Luche reduction gives cyclohex-2-en-1-ol (B-I); H2/Pd (1 eq.) gives cyclohexanone (C-IV); LiAlH4 reduces both double bond and carbonyl to yield cyclohexanol (D-II).
Reviewed route
Solution
StepWorking
01identify
The substrate is 4-tert-butylcyclohexanone. List I contains various reagents: A. CH3MgBr followed by H3O+, B. LiAlH4, C. CH3MgBr/H3O+ followed by H2SO4/Δ, and D. LiAlH4 followed by H2SO4/Δ.
02mechanism
For A: Nucleophilic addition of CH3MgBr to the carbonyl carbon gives a tertiary alcohol, 4-tert-butyl-1-methylcyclohexan-1-ol (Structure III). Thus, A matches III.
03mechanism
For B: Hydride reduction of the ketone with LiAlH4 gives a secondary alcohol, 4-tert-butylcyclohexan-1-ol (Structure I). Thus, B matches I.
04mechanism
For C: Grignard addition forms the tertiary alcohol (III), which upon acid-catalyzed dehydration (H2SO4/Δ) eliminates water to yield the most stable, endocyclic trisubstituted alkene: 4-tert-butyl-1-methylcyclohex-1-ene (Structure IV). Thus, C matches IV.
05mechanism
For D: Reduction forms the secondary alcohol (I), which upon acid-catalyzed dehydration (H2SO4/Δ) gives 4-tert-butylcyclohex-1-ene (Structure II). Thus, D matches II.
06product
Matching pairs are: A -> III, B -> I, C -> IV, D -> II.
✓verify
Matching A-III and B-I immediately rules out options 0, 1, and 2, confirming Option 3 as the unique correct answer.
✓ Source and academic review↓
Question type
Single correct
Exam relevance
JEE Main · Chemistry
Concepts assessed
Chemistry
Academic status
Reviewed by official_key
Source
pyq
Editorial review
7 September 2026
Quick checks
Students also ask
Why does dehydration of 4-tert-butyl-1-methylcyclohexanol give IV instead of an exocyclic double bond?
Zaitsev's rule dictates formation of the more stable, more highly substituted endocyclic alkene (trisubstituted).