42 / 58
40
results of the observation? The reaction of salicylic acid with FeCl
3
takes place
according to the following scheme:
+
+
2HCl
FeCl
3
OH
C
OH
O
O
C
O O
FeCl
Experiment 4. Proof of the absence of phenolic hydroxyl in aspirin and its
hydrolysis.
Place a grain of aspirin in the tube and add 5–6 drops of water.
Shake the tube until completely dissolved. Divide the solution into two parts
and boil one of the parts for 0.5 min. Add 1 drop of 1% solution of FeCl
3
in
both tubes. Compare the color of the solution in both test tubes. What is the
conclusion from this? If both test tubes are stained, what conclusion can be
drawn about the quality of aspirin?Write the equation of hydrolysis of aspirin:
+
+
CH
3
COOH
H
2
O
O
COOH
C
O
CH
3
OH
COOH
Experiment 5. Proof of the presence of phenolic hydroxyl in salol.
Place a grain
of salol into the tube and add 2 drops of ethyl alcohol to dissolve, add 1 drop of 1%
solution of FeCl
3
to the resulting solution.Appears red-violet staining, characteristic
of the free phenolic group (see the equation of interaction of FeCl
3
with phenol).
Add 2–3 drops of water to the test tube. The liquid becomes turbid due to the loss
of salol due to its insolubility in water. At the same time, the color of the solution
disappears. Write the equation for the reaction of salol with FeCl
3.
LESSON 18.
CHEMISTRY OF SIMPLE LIPIDS
Required base level.
The structure and properties of polyhydric alcohols, including glycerin.
Structure and properties of carboxylic acids. Structure, production and properties
of esters. Structure and properties of unsaturated hydrocarbons.
Questions for the preparation for the lesson.
1. Lipids. Definition, classification of lipids by structure, with respect to
hydrolysis, by biological role.