Question

The structures of major products A , B and C in the following reaction are sequence

• A.
• B.
• C.
• D.

Hint:

Pay attention to the reagents and reaction conditions to identify the type of reaction occurring in each step. \(LiAlH_{4}\) is a strong reducing agent, commonly used to reduce nitriles to amines.

Answer 1

The Correct Option is C

Step 1: Reaction with\(NaHSO_{3}\) and Dilute HCl (Formation of A)
The starting compound is butan-2-one. The reaction with \(NaHSO_{3}\)followed by dilute HCl results in the formation of a cyanohydrin. The CN\(^-\) ion from NaCN attacks the carbonyl carbon, and the oxygen picks up a proton. The major product \(A\) is 2-hydroxy-2-methylbutanenitrile.
Step 2: Reduction with\(LiAl_{4}\) (Formation of B)
Lithium aluminum hydride \(LiAlH_{4}\)is a strong reducing agent. It reduces the nitrile group (CN) to an amine group \((NH_{2})\). The product \(B\) is 1-amino-2-methylbutan-2-ol.
Step 3: Hydrolysis with \(HCl/H_{2}O\) and Heat (Formation of C)
The amine group in \(B\) is hydrolyzed with \(HCl/H_{2}O\)and heat (\( \Delta \)) into a carboxylic group. 
The major product \(C\) is 2-hydroxy-2-methylbutanoic acid.
Conclusion
The structures of \(A\), \(B\), and \(C\) correspond to option (4).