Question

Which of the following does not undergo Aldol condensation?

• A. Propionaldehyde
• B. Acetone
• C. Formaldehyde
• D. Acetaldehyde

Answer 1

The correct option is C

Formaldehyde

Explanation for the correct option:

(C) Formaldehyde

Aldol Condensation:

• Aldol condensation reaction is a two-step process.
• First of all, there is an aldol reaction and after that, there is a condensation reaction in which water or any other small molecule is removed (mostly water).
• There is a mandatory requirement for the presence of alpha $\left(\mathrm{\alpha }\right)$ hydrogen in the aldehydes or ketones taken to undergo the reaction.

Among all the given compounds, formaldehyde$\left({\mathrm{CH}}_2\mathrm{O}\right)$ is the only compound that does not have any alpha hydrogen. Therefore it cannot undergo an aldol condensation reaction.

Explanation for incorrect options:

Propionaldehyde$\left({\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{CHO}\right)$, Acetone$\left({\left({\mathrm{CH}}_3\right)}_2\mathrm{CO}\right)$, and Acetaldehyde$\left({\mathrm{CH}}_3\mathrm{CHO}\right)$ undergo aldol condensation as they have alpha hydrogen. Thus options A, B, and D are incorrect.

Hence, the correct option is C i.e. Formaldehyde.