Laboratory Experiments of B.Sc. II Sem BT/FS/CBZ - Experiment: 1
Laboratory
Experiments of B.Sc. II Sem BT/FS/CBZ
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+H2N−NH−C6H3(NO2)2→R2C=NNH−C6H3(NO2)2+H2O
Procedure:
- Place 5 ml of the 2,4-dinitrophenylhydrazine reagent in a
test tube.
- Add 2 ml of the carbonyl
compound; sharply tap the test tube with your finger to mix.
- If yellow, orange or red precipitate
does not form immediately, gently heat in a water bath (60oC)
for 5 min.
- Cool in an ice bath until crystals form.
- Filter
the crystals using a filter paper and funnel.
- Wash
the precipitate with cold distilled water to remove excess reagents.
- Allow
the product to dry in air or use gentle heating to remove moisture.
- 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.
Comments
Post a Comment