Question

Arrange the following carbonyl compounds in the decreasing order of their reactivity towards nucleophilic addition reaction:
(A) CH₃CHO
(B) HCHO
(C) Cl₃CCHO
(D) CH₃COCH₂CH₃
Choose the correct answer from the options given below:

• A. A >B >C >D
• B. B >A>D>C
• C. B >C >A>D
• D. C >B >A>D

Hint:

Electron-withdrawing groups such as Cl reduce nucleophilic attack, making compounds like CHO less reactive.

Answer 1

The Correct Option is C

The reactivity of carbonyl compounds in nucleophilic addition is affected by the electron-withdrawing or electron-donating nature of substituents. Increased reactivity is observed with fewer electron-withdrawing groups. Therefore, the reactivity order is as follows:

Formaldehyde, B (HCHO), exhibits the greatest reactivity.

Chloral, C (Cl₃CHO), is next due to the electron-withdrawing effect of the three -Cl groups.

Acetaldehyde, A (CH₃CHO), is less reactive than Chloral (C).

Ethyl methyl ketone, D (CH₃COCH₂CH₃), demonstrates the lowest reactivity due to steric hindrance from the ethyl group.