Meilen, 18.11.2007
Organic chemistry practical course (OCPI)
HS 07
529-0229-00
Fabienne Vukotic
06-910-541
D-BIOL
Assistant: Guo Xiaoqiang
Synthesis of
9-Fluorenol
1. Method
The method for the synthesis of 9-Fluorenol is a reduction of 9-Fluorenone with
NaBH4. is an electrophilic aromatic substitution reaction: A Friedl-Crafts
alkylation of o-xylene with a tert-butyl group from tert-butyl chloride with Iron
(III) chloride – a Lewis acid – as catalyst.
2. Reaction Equation
NaBH 4
O
OH
3. Mechanism
NaBH4 is chemoselective for keto groups:
H
O
H
Na
Na
B
H
NaBH4
O
1 eq.
O
H
H
B
O
H
H
B
H
H
H
4 eq.
can hydrate three
more keto groups
3 H2 O, H
B(OH)3
+
OH
B O
4
4 eq.
4. Physical and Chemical Properties of Substances
9-fluorenone
CAS: 486-25-9
M: 180.21 g/mol
d: 0.9 g/mL
bp: 342 °C
mp: 80-83 °C
Safety Phrases
-S22: Do not breathe dust
-S24/25: Avoid contact with skin and eyes
Methanol
CAS: 67-56-1
M: 32.04 g/mol
d: 0.791 g/mL
bp: 64.7 °C
mp: -98 °C
n20D: 1.3288
MAK: 260 mg/m3, 200 mL/m3
CH-toxicity class: 3
Risk Phrases
-R11: Highly Flammable
-R23/24/25: Toxic by inhalation, in contact with
skin and if swallowed
-R39/23/24/25: Toxic: danger of very serious
irreversible effects through inhalation, in contact
with skin and if swallowed
Safety Phrases
-S7: Keep container tightly closed
-S16: Keep away from sources of ignition - No
smoking
-S36/37: Wear suitable protective clothing and
gloves
-S45: In case of accident or if you feel unwell,
seek medical advice immediately (show label
where possible)
Sodium borohydride
CAS: 16940-66-2
M: 37.83 g/mol
d: 0.4 g/mL
CH-toxicity class: 3
mp: 500 °C
Risk Phrases
-R15: Contact with water liberates extremely
flammable gases
-R24/25: Toxic in contact with skin and if
swallowed
-R34: Causes burns
NaBH4
Safety Phrases
-S22: Do not breathe dust
-S26: In case of contact with eyes, rinse
immediately with plenty of water and seek
medical advice
-S36/37/39: Wear suitable protective clothing,
gloves and eye/face protection
-S43: In case of fire, use ... (indicate in the space
the precise type of fire-fighting equipment.
Never use water)
-S45: In case of accident or if you feel unwell,
seek medical advice immediately (show label
where possible)
Sulfuric acid (25%)
CAS: 7664-93-9
M: 98.08 g/mol
d: 1.18 g/mL
bp: 103 °C
Risk Phrases
-R35: Causes severe burns
Safety Phrases
-S26: In case of contact with eyes, rinse
immediately with plenty of water and seek
medical advice
-S30: Never add water to this product
-S45: In case of accident or if you feel unwell,
seek medical advice immediately (show label
where possible)
9-fluorenol
CAS: 1689-64-1
M: 182.22 g/mol
mp153-154 °C
Safety Phrases
-S24/25: Avoid contact with skin and eyes
5. Experimental Setup
setup for reduction
vacuum filtration
safety bottle
100
100 mL
75
50
500 mL
LaboBib©
300
50
AN
AN
AUS
AUS
1500
100
o
0 U/min
250
500
C
200
150
1000
750
vacuum
reflux:
20o
20o
NS 14
20o
250 mL
LaboBib©
300
50
AN
AN
AUS
AUS
1500
0 U/min
250
500
100
o
C
200
150
1000
750
6. Amounts of Substance used
Substance
measured
amount [ml]
[g]
[mmol]
eq
9-Fluorenone
0.60
3.3
2.5
Methanol
8.5
6.7
210
159
NaBH4
0.0498
1.32
1.0
H2SO4 (3M)
2.0
6.0
4.5
9-Fluorenone is the limiting reactant. NaBH4 is excess because it can not
always hydrate 4 keto groups since they are very large groups.
7. Experimental Section (Procedure)
0.60 g of 9-Fluorenone is added to 6.0 mL methanol and heated until all 9fluorenone is dissolved. The solution is now yellow. After it has cooled down to
RT, 0.0498 g NaBH4 is added and dissolved. It is allowed to stand at RT for
20min and is swirled occasionally. The solution turns to colorless again. 2.0 mL
H2SO4 is added and a white precipitate forms. The contents in the flask are
heated below the reflux point, 2.5 mL of methanol is added in 0.5 mL portions
until a solution is obtained. The solution is allowed to cool to RT again and
then is put in an ice bath for 10min. The substance is vacuum filtrated and
washed thoroughly with distilled water until the filtrate is neutral. The
substance is air-dried over night.
The solid substance is now recrystallized and therefore put in a 50 mL twoneck round bottom flask and 0.8 mL distilled water and 5.3 mL methanol is
added (a ratio of 1:5 would be optimal). It is heated to boiling under reflux
and is then allowed to cool down. The product is vacuum filtrated and
washed with distilled water. It is dried in the hot oven for 12h and then
characterized.
8. Yield
The theoretical yield is 3.33 mmol. The experimental yield is 0.349 g =
1.92 mmol.
The yield percentage therefore is 57.5%
9. Characterization
Melting point
A melting point range of 154.0 – 154.9 °C was measured. The literature value
for 9-fluorenol is 153-154 °C.
IR-Spectrum (see attachement)
bands [cm-1]
3298
~3030
1607
1450
interpretation
O-H
unsat. C-H
aromatic ring
Literature spectrum
http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/direct_frame_top.cgi
10. Remarks and Discussion
The melting point is a little bit too high. The IR spectrum is not very good and it
shows impurities.
11. Literature
Coblentz Society, Inc., "Evaluated Infrared Reference Spectra" in NIST
Chemistry WebBook, NIST Standard Reference Database Number 69,
Eds. P.J. Linstrom and W.G. Mallard, June 2005, National Institute of
Standards and Technology, Gaithersburg MD, 20899. NIST Chemistry
Webbook. 27. Oct. 2007 <http://webbook.nist.gov>.
EMolecules - Searching the World's Chemistry. 2007. EMolecules, Inc. 28 Oct.
2007 <http://www.emolecules.com>.
IGS Giftliste. 31 July 2007. BAG. 28 Oct. 2007
<http://igs.naz.ch/igs/igsServer/de.kisters.igs.igs40.servlets.igs40Servlet>.
Kirste, Burkhard. "Chemikalien: Sicherheitsdaten." Institut für Chemie und
Biochemie an der FU Berlin. 28 July 1994. FU Berlin. 27 Oct. 2007
<http://www.chemie.fu-berlin.de/chemistry/safety/chemsafety.html>.
"Risk & Safety." Sigma-Aldrich. 2007. Sigma-Aldrich Co. 27 Oct. 2007
<http://www.sigmaaldrich.com/Help_Pages/Help_Welcome/Product_
Search/Risk___Safety_Statements.html#Safety%20Phrases>.
Sigma-Aldrich. 2007. Sigma-Aldrich Co. 27 Oct. 2007
<http://www.sigmaaldrich.com/Area_of_Interest/Europe_Home/
Switzerland__Schweiz_.html>.