Question

What is the correct sequence of increasing reactivity of the following compounds towards nucleophilic addition reaction? (A) Ethanal
(B) Propanone
(C) Propanal
(D) Butanone

• A. (A), (B), (C), (D)
• B. (D), (B), (C), (A)
• C. (A), (C), (B), (D)
• D. (C), (B), (D), (A)

Hint:

Aldehydes are generally more reactive towards nucleophilic addition than ketones because they experience less steric hindrance and the carbonyl carbon is more electrophilic.

Answer 1

The Correct Option is A

Step 1: Nucleophilic Addition Mechanism.
Nucleophilic addition reactions occur when a nucleophile attacks the carbonyl carbon (C=O) in aldehydes and ketones. Reactivity is influenced by steric bulk and electronic effects surrounding the carbonyl group.
Step 2: Compound Analysis.
- (A) Ethanal: An aldehyde, generally more reactive than ketones due to minimal steric hindrance.
- (B) Propanone: A ketone with two methyl groups adjacent to the carbonyl carbon, resulting in lower reactivity compared to aldehydes.
- (C) Propanal: An aldehyde, similar to ethanal but with a propyl substituent, leading to slightly reduced reactivity versus ethanal.
- (D) Butanone: A ketone featuring larger alkyl groups, rendering it the least reactive in nucleophilic addition.
Step 3: Determination of Reactivity Order.
The order of increasing reactivity is as follows:
(1) (A) Ethanal → (2) (B) Propanone → (3) (C) Propanal → (4) (D) Butanone.
Final Answer: \[\boxed{\text{The correct sequence is (A), (B), (C), (D).}}\]