a) 2,4-DNP Test for Aldehydes and Ketones
Aldehyde or Ketone
Cyclohexanone, Benzophenone, and Benzaldehyde
Add a solution of 1 or 2 drops or 30 mg of unknown in 2 mL of 95% ethanol to 3 mL of 2,4-dinitrophenylhydrazine reagent. Shake vigorously, and, if no precipitate forms immediately, allow the solution to stand for 15 minutes.
The 2,4-dinitrophenylhydrazine reagent will already be prepared for you.
Formation of a precipitate is a positive test.
ii) Gattermann reaction