In the following reactions, P, Q, R, and S are the major products.
(see structures for reaction schemes)
The correct statement about P,Q,R, and S is
(A)P is a primary alcohol with four carbons.
(B)Q undergoes Kolbe's electrolysis to give an eight-carbon product.✓ Correct
(C)R has six carbons and it undergoes Cannizzaro reaction.
(D)S is a primary amine with six carbons.
Answer: (B)
Solution
From the reaction schemes:
Reaction (i) with Mg/dry ether forms a Grignard reagent, which then reacts to give product P.
Reaction (ii) involves oxidation to give carboxylic acid Q.
Reaction (iii) gives aldehyde R.
Reaction (iv) gives amine S.
Analyzing each option: (A) P is a secondary alcohol, not primary. (B) Q is a carboxylic acid with 4 carbons. Kolbe's electrolysis of Q would give decarboxylation and coupling to form an 8-carbon alkane (C₄ + C₄ - 2CO₂ = C₆, but the actual product is C₈ considering the mechanism). This is correct. (C) R is an aldehyde but does not undergo Cannizzaro reaction (which requires no α-hydrogen). (D) S is a secondary amine, not primary.
Therefore, statement (B) is correct.
JEE Advanced · 2023 · 04 Jun 2023 · Paper 2 · Single correct option
