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Choose the incorrect statement among the following.
A. The reactivity of aromatic aldehydes and ketones is less than that of aliphatic carbonyl compounds towards nucleophilic addition reactions.
B. Benzaldehyde does not give Fehling's test.
C. The \(\mathrm{H}\)-atoms in ethanal are acidic in nature.
D. \(p\)-nitro benzaldehyde is less reactive than benzaldehyde towards nucleophilic addition reactions.
Options:
A. The reactivity of aromatic aldehydes and ketones is less than that of aliphatic carbonyl compounds towards nucleophilic addition reactions.
B. Benzaldehyde does not give Fehling's test.
C. The \(\mathrm{H}\)-atoms in ethanal are acidic in nature.
D. \(p\)-nitro benzaldehyde is less reactive than benzaldehyde towards nucleophilic addition reactions.
Solution:
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Verified Answer
The correct answer is:
D
(A) Because of the attachments of bulkier groups (aryl), the attack of nucleophile to the \(s p^2\) carbon of \( > \mathrm{C}=\mathrm{O}\) group will face steric repulsion.
So, rate of the reaction will decrease.
(B) Fehling's solution is being a very mild oxidising agent, benzaldehyde does not respond to it.
(C) Ethanol on tautomerisation produces its enol form. It atom attacked with \(\mathrm{OH}\) group of the enol is acidic.
(D) Because of the presence of \(-\mathrm{NO}_2\) group of para position ( \(-R\) effect), the carbon atom \(\left(s p^2\right)\) of
group becomes more susceptible for nucleophilic attack as the \(s p^2\) carbon gains more partial positive charge.
So, this statement is not correct.
So, rate of the reaction will decrease.
(B) Fehling's solution is being a very mild oxidising agent, benzaldehyde does not respond to it.
(C) Ethanol on tautomerisation produces its enol form. It atom attacked with \(\mathrm{OH}\) group of the enol is acidic.
(D) Because of the presence of \(-\mathrm{NO}_2\) group of para position ( \(-R\) effect), the carbon atom \(\left(s p^2\right)\) of
group becomes more susceptible for nucleophilic attack as the \(s p^2\) carbon gains more partial positive charge.
So, this statement is not correct.
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