The product formed by the reaction of an aldehyde with a primary amine is:

Solution & Explanation

\textbf{Answer:} (A) A primary amine condenses with an aldehyde to give an N-substituted imine (Schiff base). \textbf{Solution:} The lone pair on the nitrogen of a primary amine attacks the electrophilic carbonyl carbon of an aldehyde, giving a carbinolamine (hemiaminal) intermediate, which then loses water to form a carbon$\to$nitrogen double bond. $\mathrm{R}-\mathrm{CHO}+\mathrm{H}{}_2\mathrm{N}-\mathrm{R}{}^{\prime }\to \mathrm{R}-\mathrm{CH}(\mathrm{OH})-\mathrm{NH}-\mathrm{R}{}^{\prime }\stackrel{-\mathrm{H}{}_2\mathrm{O}}{\to }\mathrm{R}-\mathrm{CH}=\mathrm{N}-\mathrm{R}{}^{\prime }$ The product $\mathrm{R}-\mathrm{CH}=\mathrm{N}-\mathrm{R}{}^{\prime }$ is an imine, commonly called a \textbf{Schiff base}. No oxidation occurs, so neither a ketone, carboxylic acid, nor an aromatic acid is formed. Hence option (A) is correct.