Experiment 3: Electrophilic Aromatic Substitution
1a. The desired product did not recrystallize because too much solvent may have been added, so
the solution was not saturated. Also, the solvent may have been soluble in the solvent when hot
and cool.
1b. Crystallization can be induced by scratching the side of the reaction vessel with a glass rod or
by adding a small crude sample crystal because both will create nucleation sites. Also, it can be
induced by putting the reaction vessel in an ice-water bath. The desired product should be
insoluble when the solvent is cool, so the ice-water bath will cool it past room temperature.
2d.
Structure
Proton
Integration
# of
Normalized
Hydrogens
Hydrogens
A
-
1
-
B
-
1
-
C
3.0
3
1.0
2.16
4
0.54
0.40
2
0.20
Total
1.54
D
E
F
G
H
1
0.835
I
0.67
2
0.335
J
0.60
2
0.30
K
-
1
-
L
-
1
-
M
0.28
1
0.28
N
0.34
1
0.34
O
0.27
1
0.27
P
0.28
1
0.28
1.17
3.545
Mole Ratios:
Product: 1.54/3.545 = 0.43
4-nitroaniline: 0.835/3.545 = 0.24
Salicylic Acid: 1.17/3.545 = 0.33
Mole Percentages:
Product: 0.43 * 100 = 43%
4-nitroaniline: 0.24 * 100 = 24%
Salicylic Acid: 0.33 * 100 = 33%
2e. Recrystallization was not successful in isolating the desired product because 4-nitroaniline
and salicylic acid were present on the spectra. There’s a low yield (43%) of the desired product,
so there may have been errors during the synthesis of the amu dye (maybe, to give the reaction
2
more time to proceed, the reaction mixture needed to cool in the ice-water bath longer because
the reaction occurs at 0°C)
3