Fundamental Organic Chemistry

1-Formaldehyde
H
O
C
H
Formaldehyde is a gas and is available as aqueous solution which has a
characteristic pungent odor.
Test
Observation
Result
2,4-dinitrophenyl hydrazine test:
In a test tube put 1 ml of HCHO
+1ml of 2,4- dinitro phenyl
hydrazine .
Yellow precipitate is
formed.
The ppt. is hydrazone
derivative this prove that
formaldehyde contain
carbonyl group (16) .
O 2
N NHNH 2 + O C
H
H
- H 2
O
O 2
N
NHN
C
H
H
+ H 2
O
NO 2
NO 2
2,4-dinitrophenyl- hydrazine Formaldehyde Hydrazone derivative …(16)
2-Schiff’s Reagent:
In a test tube put 1 ml of HCHO
+ drops of Schiff’s reagent.
3-Reduction Reaction
A)- Ammonical AgNO 3
In a test tube put 1ml of HCHO
+3 ml of amm. AgNO 3 & heat in
water bath for 3 min.
Magenta color
appears rapidly.
A silver mirror is
deposited on the inner
wall of the test tube.
It’s Formaldehyde
Due to Oxidation of
HCHO to formic acid
& reduction for Ag 2 O to
Ag metal (17).
46