MCQMediumJEE 2026Alcohols

JEE Chemistry 2026 Question with Solution

Reaction scheme showing cyclohexyl-CH2-CH2-NH2 treated with C6H5COCl and NaOH to form intermediate A, then LiAlH4 and H2O to form product B.

The final product [B] is:

Four organic structure options shown vertically, including two amides, one secondary amine linking cyclohexylmethyl and benzyl groups, and one amino alcohol derivative.
  • A

    C6H5-CH2-NH-CO-cyclohexyl\text{C}_6\text{H}_5\text{-CH}_2\text{-NH-CO-cyclohexyl}

  • B

    Cyclohexyl-CH2-NH-CO-C6H5\text{Cyclohexyl-CH}_2\text{-NH-CO-C}_6\text{H}_5

  • C

    Cyclohexyl-CH2-NH-CH2-C6H5\text{Cyclohexyl-CH}_2\text{-NH-CH}_2\text{-C}_6\text{H}_5

  • D

    Cyclohexyl-CH2-NH-CH(OH)-C6H5\text{Cyclohexyl-CH}_2\text{-NH-CH(OH)-C}_6\text{H}_5

Answer

Correct answer:C

Step-by-step solution

Standard Method

Given: The starting compound is a primary aliphatic amine reacting first with benzoyl chloride in NaOH, then with LiAlH4\text{LiAlH}_4 followed by H2O\text{H}_2\text{O}.

Find: The final product [B][B].

Step 1: Identify the first reaction.

The starting compound is a primary aliphatic amine. Reaction with benzoyl chloride (C6H5COCl)\left(\text{C}_6\text{H}_5\text{COCl}\right) in the presence of NaOH gives an amide via Schotten–Baumann reaction.

Thus, intermediate [A][A] is:

Cyclohexyl-CH2-NH-CO-C6H5\text{Cyclohexyl-CH}_2\text{-NH-CO-C}_6\text{H}_5

Step 2: Effect of LiAlH4\text{LiAlH}_4.

LiAlH4\text{LiAlH}_4 reduces amides to amines, converting the CO-\text{CO}- group into a CH2-\text{CH}_2- group.

Therefore:

-NH-CO-C6H5LiAlH4-NH-CH2-C6H5\text{-NH-CO-C}_6\text{H}_5 \xrightarrow{\text{LiAlH}_4} \text{-NH-CH}_2\text{-C}_6\text{H}_5

Step 3: Write the final product.

The final compound [B][B] is:

Cyclohexyl-CH2-NH-CH2-C6H5\text{Cyclohexyl-CH}_2\text{-NH-CH}_2\text{-C}_6\text{H}_5

This structure matches the third structure in the provided figure.

The solution states Option (D), but its worked structure corresponds to the third displayed option. Therefore, the defensible answer from the actual chemistry is C.

Reaction Interpretation

Given: Benzoylation of a primary amine is followed by reduction with LiAlH4\text{LiAlH}_4.

Find: Which displayed structure is product [B][B].

Benzoyl chloride first converts the amine into an NN-benzoyl derivative, so the nitrogen becomes part of an amide linkage.

R-NH2R-NH-CO-C6H5\text{R-NH}_2 \rightarrow \text{R-NH-CO-C}_6\text{H}_5

Reduction of an amide with LiAlH4\text{LiAlH}_4 does not retain the carbonyl oxygen. Instead, the carbonyl carbon remains in the chain as a methylene group.

R-NH-CO-R’R-NH-CH2-R’\text{R-NH-CO-R'} \rightarrow \text{R-NH-CH}_2\text{-R'}

So the benzoyl fragment becomes a benzyl fragment, and the product is the secondary amine:

Cyclohexyl-CH2-NH-CH2-C6H5\text{Cyclohexyl-CH}_2\text{-NH-CH}_2\text{-C}_6\text{H}_5

Hence, the correct displayed choice is C.

Common mistakes

  • Assuming benzoyl chloride gives a substituted amine directly is incorrect because the first step forms an amide, not an alkylated amine. First write the Schotten–Baumann product, then apply reduction.

  • Keeping the carbonyl group after LiAlH4\text{LiAlH}_4 reduction is incorrect because amides are reduced to amines with the CO-\text{CO}- unit converted into CH2-\text{CH}_2-. Replace the carbonyl oxygen-containing part accordingly.

  • Trusting the printed option label without checking the worked structure can be misleading here. The solution text says D, but the derived structure matches the third displayed option, so always compare the actual product structure with the drawings.

Practice more Alcohols questions

Get unlimited AI-adaptive practice, mastery tracking, and an AI tutor that explains every step — free to start.

Related questions