Question

Hydroxamic acid test is employed to detect

• A. ketones
• B. aldehydes
• C. esters
• D. amides

Answer 1

Answer: (C)

esters

Answer 2

Hydroxamic acid test is used to detect the presence of esters.
In hydroxamic acid test a few crystals or a few drops of the substance is dissolved in $1\, mL$ of $95 \%$ ethanol $+1\, mL$ of $1\, M\,HCl$.
Then, a drop of $5 \% FeCl _{3}$ is added.
Formation of characteristic colour shows the presence of acyl or ester group.