Directions: In the following questions, A statement of Assertion (A) ...
The carbon atom of the carbonyl group of benzaldehyde is less electrophilic than carbon atom of carbonyl group present in ethanal. The polarity of the carbonyl group is reduced in benzaldehyde due to resonance hence it is less reactive than ethanal towards nucleophilic addition reaction.
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Directions: In the following questions, A statement of Assertion (A) ...
Assertion (A): Benzaldehyde is less reactive than ethanal towards nucleophilic addition reactions.
Reason (R): Ethanal is more sterically hindered.
The correct answer is option 'B' - Both A and R are true but R is NOT the correct explanation of A.
Explanation:
Nucleophilic addition reactions involve the addition of a nucleophile to a carbonyl group, resulting in the formation of a new bond. In this case, we are comparing the reactivity of benzaldehyde and ethanal towards nucleophilic addition reactions.
Reactivity of Benzaldehyde:
Benzaldehyde has a phenyl group attached to the carbonyl carbon. The presence of the phenyl group in benzaldehyde makes the carbonyl carbon less electrophilic compared to that in ethanal. This is because the phenyl group is electron-donating and destabilizes the partial positive charge on the carbonyl carbon. Therefore, benzaldehyde is less reactive towards nucleophilic addition reactions compared to ethanal.
Reactivity of Ethanal:
Ethanal does not have any bulky substituents attached to the carbonyl carbon. Therefore, the carbonyl carbon in ethanal is more electrophilic compared to that in benzaldehyde. This makes ethanal more reactive towards nucleophilic addition reactions.
Steric Hindrance:
The reason provided in the statement (R) is that ethanal is more sterically hindered. Steric hindrance refers to the obstruction of a reaction due to the presence of bulky substituents. However, this reason is not correct in this context. Ethanal is actually less sterically hindered compared to benzaldehyde because it does not have any bulky substituents. Therefore, the reason provided is not the correct explanation for the difference in reactivity between benzaldehyde and ethanal.
In conclusion, both the assertion and reason are true, but the reason is not the correct explanation for the assertion. Hence, the correct answer is option 'B' - Both A and R are true but R is NOT the correct explanation of A.