Question
Question: Which of the following compounds is least reactive towards nucleophilic addition reactions?...
Which of the following compounds is least reactive towards nucleophilic addition reactions?
A
Formaldehyde
B
Acetaldehyde
C
Butyraldehyde
D
Benzaldehyde
Answer
Benzaldehyde
Explanation
Solution
In nucleophilic addition, the reactivity of the carbonyl compound is directly related to the electrophilicity of the carbonyl carbon. Formaldehyde, with no alkyl substituents, is most electrophilic and thus more reactive. Benzaldehyde, however, has a phenyl group that donates electron density by resonance, reducing the electrophilicity of the carbonyl carbon. Therefore, benzaldehyde is the least reactive towards nucleophilic addition.
Benzaldehyde's phenyl group stabilizes the carbonyl carbon via resonance, lowering its electrophilicity and making it less reactive to nucleophilic attack.