Laboratory Experiments of B.Sc. II Sem BT/FS/CBZ - Experiment: 1

Laboratory Experiments of B.Sc. II Sem BT/FS/CBZ

 

Dr. Navdeep Sharma
Institute of Sciences
SAGE University, Indore (M.P.)

 

Experiment 1

Objective: Synthesis of 2, 4-Dinitrophenylhydrazone Derivative

 

Material  Required

2,4-Dinitrophenylhydrazine (DNP or DNPH)

Carbonyl compound (Aldehyde or Ketone)

Ice bath

Beaker (100 mL)

Stirring rod

Filter paper

Funnel

Principle

The reaction between 2,4-dinitrophenylhydrazine (DNPH) and a carbonyl compound (aldehyde or ketone) is a condensation reaction that forms a 2,4-dinitrophenylhydrazone derivative with the elimination of water. The reaction occurs due to the nucleophilic attack of the hydrazine's -NH₂ group on the electrophilic carbonyl carbon, leading to the formation of a stable C=NNH bond. This reaction is widely used for the identification of aldehydes and ketones, as the resulting yellow, orange, or red precipitate has a distinct melting point, which helps in compound characterization.

 

R2C=O+H2NNHC6H3(NO2)2R2C=NNHC6H3(NO2)2+H2O

 

 

Procedure:

  1. Place 5 ml of the 2,4-dinitrophenylhydrazine reagent in a test tube.
  2. Add 2 ml of the carbonyl compound; sharply tap the test tube with your finger to mix.
  3. If yellow, orange or red precipitate does not form immediately, gently heat in a water bath (60oC) for 5 min.
  4. Cool in an ice bath until crystals form.
  5. Filter the crystals using a filter paper and funnel.
  6. Wash the precipitate with cold distilled water to remove excess reagents.
  7. Allow the product to dry in air or use gentle heating to remove moisture.
  8. The final 2,4-Dinitrophenylhydrazone derivative is now ready for further analysis (such as melting point determination).

Observations:

  • The formation of a yellow, orange, or red precipitate confirms the presence of a carbonyl compound.

 

Result: The.............colored precipitate of 2,4-Dinitrophenylhydrazone derivative yielded.

Yield = g

 

Precautions:

  • Handle sulfuric acid with care as it is corrosive.
  • Perform the experiment in a well-ventilated area.
  • Dispose of chemical waste properly as per laboratory guidelines.

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