Degree of difficulty
Medium
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March 2006
4
Analytics
Temperature-time-dependence of the working steps in the microwave field
phenol nitration in the microwave field
0
10
20
30
40
50
60
70
0
50
100
150
200
250
300
350
400
450
Zeit [sec]
T
e
m
p
e
ra
tu
r
[°
C
]
0
100
200
300
400
500
600
700
800
900
1000
E
n
e
rg
ie
[
W
]
T1 [°C]
Energie [Watt]
mit Eisbad
Kühlen
steam distillation of o-nitrophenol in the microwave field
0
20
40
60
80
100
120
0
500
1000
1500
2000
2500
3000
3500
4000
4500
Zeiz [sec]
T
e
m
p
e
ra
tu
r
[°
C
]
0
100
200
300
400
500
600
700
800
900
E
n
e
rg
ie
[
W
]
T1 [°C]
Energie [Watt]
Reaction monitoring with GC
Sample preparation:
Before and after the microwave treatment, a sample is taken from the oil phase and
50 mg of the sample are dissolved in 1 mL dichloromethane. 3 µL from this solution
are injected.
NOP
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March 2006
5
GC-conditions:
column:
HP-5; length 30 m, internal diameter 0.32 mm, film 0.25 µm
inlet:
split injection 194:1
carriergas:
H
2
, pre-column pressure 31 kPa
oven:
3 min isotherme at 50 °C, then with 8 °C/min to 320 °C
detector:
300 °C
Percent concentration was calculated from peak areas.
GC of the reaction mixture before the microwave treatment
Retention time (min)
Substance
Peak area %
5.0
p
-benzoquinone
1
6.5
phenol
25
9.6
2-nitrophenol
34
17.2
4-nitrophenol
40
GC of the reaction mixture after the microwave treatment
Retention time (min)
Substance
Peak area %
6.0
p
-benzoquinone
4
10.4
2-nitrophenol
40
17.0
4-nitrophenol
56
NOP
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6
GC of the product 2-nitrophenol after the steam distillation
Retention time(min)
Substance
Peak area %
10.4
2-nitrophenol
> 99.5
GC of the product 4-nitrophenol
Retention time (min)
Substance
Peak area %
5.1
p
-benzoquinone
0.3
16.4
2,4-dinitrophenol
1.1
17.6
4-nitrophenol
98.6
NOP
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March 2006
7
1
H NMR spectrum of the product 2-nitrophenol
(300 MHz, CDCl
3
)
(ppm)
1
2
3
4
5
6
7
8
9
10
11
(ppm)
7.0
7.2
7.4
7.6
7.8
8.0
8.2
8.4
δ
δ
δ
δ
(ppm)
Multiplicity
Number of H
Assignment
10.58
S
1
O-H
8.10
dd,
3
J
3, 4
= 8.4 Hz
4
J
3, 5
= 1.7 Hz
1
3-H
7.58
dt,
3
J
5, 6
= 8.5 Hz
3
J
5, 4
= 8.5 Hz
4
J
5, 3
= 1.7 Hz
1
5-H
7.15
ddd,
3
J
6, 5
= 8.5 Hz
4
J
6, 4
= 1.5 Hz
5
J
6, 3
= 0.4 Hz
1
6-H
6.99
dt,
3
J
4, 3
= 8.4 Hz
3
J
4, 5
= 8.5 Hz
4
J
4, 6
= 1.5 Hz
1
4-H
7.26
solvent
OH
NO
2
1
3
4
5
6
2
NOP
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March 2006
8
13
C NMR spectrum of the product 2-nitrophenol
(300 MHz, CDCl
3
)
(ppm)
70
80
90
100
110
120
130
140
150
δ
δ
δ
δ
(ppm)
Assignment
155.1
C-1
137.5
C-5
133.7
C-2
125.1
C-3
120.2
C-4
119.9
C-6
76.5-77.5
solvent
13
C NMR spectrum of the product 4-nitrophenol
(300 MHz, acetone-D
6
)
(ppm)
40
60
80
100
120
140
160
180
200
δ
(ppm)
Assignment
164.3
C-1
141.7
C-4
126.9
C-3, C-5
116.5
C-2, C-6
206, 30
solvent
OH
NO
2
1
3
4
5
6
2
OH
NO
2
1
2
3
4
5
6
NOP
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March 2006
9
1
H NMR spectrum of the product 4-nitrophenol
(300 MHz, acetone-D
6
)
(ppm)
1
2
3
4
5
6
7
8
9
10
(ppm)
7.2
7.6
8.0
δ
δ
δ
δ
(ppm)
Multiplicity
Number of H
Assignment
9.80
s
1
O-H
8.15
d (AA´)
2
3-H, 5-H
7.02
d (XX´)
2
2-H, 6-H
2.04
acetone
3.1
water
OH
NO
2
1
2
3
4
5
6
NOP
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March 2006
10
IR spectrum of the product 2-nitrophenol
(KBr)
4000,0
3000
2000
1500
1000
400,0
0,129
0,15
0,20
0,25
0,30
0,35
0,40
0,45
0,50
0,560
cm-1
Egy
o-Nitrophenol
3446,49
3239,85
3107,01
2922,50
1944,70
1738,24
1612,90
1587,09
1531,79
1476,49
1447,00
1369,58
1310,59
1262,67
1236,86
1174,19
1129,95
1078,34
1023,04
952,99
864,51
816,58
783,41
753,91
665,43
543,77
521,65
418,43
(cm
-1
)
Assignment
3445, 3240
O-H-valence, superimposed by
C-H-valence, arene
1610, 1590
C=C-valence, arene
1530, 1310
N=O-valence, asymm. and. symm.
IR spectrum of the product 4-nitrophenol
(KBr)
4000,0
3000
2000
1500
1000
400,0
0,15
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
1,1
1,2
1,26
cm-1
Egy
p-Nitrophenol
3608,85
3365,31
3077,49
2922,50
1918,89
1697,69
1609,21
1590,78
1494,93 1340,09
1292,16
1200,00
1107,83
1052,53
842,39
746,54
691,24
624,88
599,07
536,40
488,47
(cm
-1
)
Assignment
3365
O-H-valence, superimposed by
C-H-valence, arene
1610, 1590
C=C-valence, arene
1495, 1340
N=O-valence, asymm. and. symm.
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