Question

An organic compound C₂H₄O gives a red precipitate when heated with Fehling solution. It also undergoes aldol condensation in the presence of dilute NaOH.

1. Identify the organic compound and write its IUPAC name.
2. Which compound will be formed when this organic compound reacts with hydroxylamine?
3. What is observed when the compound, referred to in subpart (i), is heated with ammonical silver nitrate?

Answer 1

1. Reacting aliphatic aldehyde with Fehling solution produces a red cuprous oxide precipitate. As a result, acetaldehyde is the required organic component.
   IUPAC Name: ethanal
2. Ethanal reacts with hydroxylamine to form Ethanal oxime.
   \[\ce{\underset{Ethanal}{CH3CHO} + H2NOH -> \underset{Ethanal oxime}{CH3 - C = NOH} + H2O}\]
3. Aldehyde is oxidised to carboxylic acid. Silver reduces into metal, resulting in a silver mirror, indicating that the chemical is Aldehyde.
   \[\begin{array}{cc}
   \ce{O}\phantom{................................................................................}\\
   ||\phantom{................................................................................}\\
   \ce{CH3 - C - H + 2[Ag(NH3)2]NO3 + 2NH4OH ->2NH4NO3 + \underset{Silver mirror}{RCOOH + 2Ag↓ + H2O} + 4NH3}
   \end{array}\]