Question

On reaction with NaNO2 and HCl, which of the following amino alcohol(s) will yield compound P? 

• A. (A)
• B. (B)
• C. (C)
• D. (D)

Hint:

In diazotization reactions, the amino group is converted into a diazonium ion, which can undergo further reactions with nucleophiles to form new products.

Answer 1

The Correct Option is B, C

Reaction conditions: NaNO₂ + HCl (diazotization conditions)

Product P: A cyclopentane ring with CHO (aldehyde) and tert-butyl group

Understanding the reaction:

When primary amino alcohols react with NaNO₂/HCl:

1. The amino group (-NH₂) is converted to a diazonium salt (-N₂⁺)
2. The diazonium group is a good leaving group
3. Water attacks, replacing N₂ with OH
4. The resulting diol undergoes pinacol-type rearrangement or oxidation

However, if the amino group and hydroxyl group are positioned such that:

• The OH can assist in departure of N₂
• A cyclic intermediate forms
• This leads to formation of an aldehyde or ketone

Key requirement: The amino alcohol must have the -NH₂ and -OH groups positioned to allow cyclization and subsequent formation of the aldehyde product P.

Analyzing the options:

(A) Linear amino alcohol with -NH₂ and -OH at different positions - unlikely to form cyclic aldehyde

(B) Cyclohexane with -NH₂ and -OH - the ring structure and positioning could allow for the rearrangement to form the cyclopentane aldehyde through ring contraction

(C) Cyclohexane with -NH₂ and -OH at adjacent positions - this positioning is ideal for the reaction. The diazonium intermediate can undergo ring contraction to form the cyclopentane aldehyde P

(D) Cyclohexane with -NH₂ and -OH - similar to B, but different stereochemistry

Answer: (B) and (C)