Zurich, 12.11.2007
Synthesis of
9-fluorenol
OH
Tobias Langenegger
tobiasla@student.ethz.ch
05-918-362
D-Biol (chem.)
assisted by
Guo Xiaoqiang
Method
Reduction of a ketone to a alcohol using sodium borohydride as reactand.
Chemical equation
NaBH4
O
OH
MeOH
Mechanism
H
H
O
B
O
H
B
H
H
H
O
O
B
O
O
H2SO4
OH
H
H
Physical and safety data
substance
Mw
(g/mol)
density
(g/cm3)
mp
(°C)
bp
(°C)
Poison
CH
R-phrases
S-phrases
9-fluorenone
C13H8O
180.2
0.9
81-85
342
-
24, 25
-
9-fluorenol
C13H10O
182.2
1.151
152-158
-
-
24, 25
-
MeOH
CH3OH
32.04
0.787
-97.8
65
3
11, 23, 24,
25, 39
7, 16, 36,
37, 45
NaBH4
37.83
1.074
36
~400
-
15, 25, 34
26, 36, 37,
38, 45
H2SO4
98.08
1.836
10.4
279.6
2
35
26, 30, 45
Equipment
Vacuum filtration:
reflux:
Preparation
Substance
9-fluorenone
methanol
NaBH4
H2SO4
eq
1
solvent
0.375
excess
n (mmol)
3.385
147.4
1.269
37.43
V (mL)
6
2
m (mg)
610
48
-
Experimental section
0.61 g 9-fluorenone was dissolved in 6 mL methanol under warming. After the
solution was cooled down to RT, 48 mg NaBH4 was dissolved and let it react for 20
min. In that time the solution turned colorless. Than 2 ml of 3 M H2SO4 were added
and the Solid product that accrued was heated with 2 pipettes of Methanol until it was
completely dissolved. After cooling down to RT the flask was put in an ice-water bath
for 15 min. Then the solid product was collected by vacuum filtration and washed with
water. After that the 9-fluorenol was purified by a mixed solvent recrystallization using
water and methanol in a ratio of 1 to 5.5. The Product was dried and characterized.
Yield
V
-
m
0.49 g
n
2.69 mmol
Yield
79.5%
Characterisation
Melting point
Peaks in IR spectrum
153.7 – 154,2 °C
~3286 cm-1
~3020 cm-1
1450 cm-1
(Literature 152 – 158 °C)
O-H
unsat. C-H
aromatic ring
Discussion
The biggest problem was to dry the product. First it was dried for 20 min in a rotavap
and for 30 min in the oven. But because it wasnʼt dry after this, it was putted in the
oven for a day, the next week. In the end it was dry, what we can se on the IR. There
isnʼt anymore this strong water peak, which was on the first IR.
Literature
https://www.discoverygate.com/
http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/direct_frame_top.cgi
http://www.chemexper.com/
http://www.wikipedia.org
Attachment
-
Reference IR spectrum
Copy of the lab notebook
-
IR spectrum
Reference IR spectrum from
http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/direct_frame_top.cgi