Synthesis of Triphenylmethanol
by Markus Arnoldini
Laboratory Report
Synthesis of
Triphenylmethanol
OH
by Markus Arnoldini
1
Synthesis of Triphenylmethanol
1.
by Markus Arnoldini
Method
Grignard reaction.
2.
Reaction Equation
O
Br
+
3.
+
Mg +
OH
H2O
Mechanism
first step:
Br
+ Mg - Mg - Mg
Br
+
Mg - Mg - Mg
+
Br
+ Mg - Mg - Mg
MgBr
2
+
2
Mg
+
Br
Synthesis of Triphenylmethanol
by Markus Arnoldini
second step:
O
O2Et
EtO2
Mg
Br
+
Ligandchange
O
Mg
Br
O2Et
Nucleophilic
Attack
MgBr
Et2O
OEt2
Et2O
O
Mg
O
Mg
O2Et
EtO2
Mg
+
Br
Et2O
BrH
Mg
Br
Br
OEt2
Ligandchange
OEt2
OHMg
OEt2
third step:
OMgBr
OH
H
+
H2O
3
MgBr(OH)
Synthesis of Triphenylmethanol
4.
by Markus Arnoldini
Physical properties of the substances
Magnesium (slivers) [1]
molar weight
density
melting point
boiling point
refraction index
WGK
GK (CH)
R-phrases
Mg
S-phrases
24.31 g/mol
1.75 g/cm3 (20 ºC)
651 ºC
1107 ºC
nwg
R 11 (Highly flammable)
R 15 (Contact with water
liberates extremely
flammable gases)
S 7/8 (Keep container
tightly closed and dry)
S 43 (In case of fire use
sand. Never use water)
Iodine (crystal) [1]
molar weight
density
melting point
boiling point
refraction index
WGK
GK (CH)
R-phrases
I2
S-phrases
253.81 g/mol
4.93 g/cm3 (20 ºC)
114 ºC
185 ºC
1
2
R 20/21 (Harmful by
inhalation and in contact
with skin)
-
Sodium Hydrogencarbonate [1]
O
C
HO
O
Na
molar weight
density
melting point
boiling point
refraction index
WGK
GK (CH)
R-phrases
S-phrases
4
84.01 g/mol
2.22 g/ cm3
270 °C
1
5
-
Synthesis of Triphenylmethanol
by Markus Arnoldini
Diethylether (anhydrous) [1]
molar weight
density
melting point
boiling point
refraction index
WGK
GK (CH)
R-phrases
O
S-phrases
74.12 g/mol
0.71 g/cm3
-116.3 ºC
34.6 ºC (1013 hPa)
1
4
R 12 (Extremely
flammable)
R 19 (May form explosive
peroxides)
R 22 (Harmful if
swallowed)
R 66 (Repeated exposure
may cause skin dryness or
cracking)
R 67 (Vapours may cause
drowsiness and dizziness)
S 9 (Keep container in a
well-ventilated place)
S 16 (Keep away from
sources of ignition - No
smoking)
S 29 (Do not empty into
drains)
S 33 (Take precautionary
measures against static
discharges)
Benzophenone [1]
O
molar weight
density
melting point
boiling point
refraction index
WGK
GK (CH)
R-phrases
S-phrases
5
182.22 g/mol
1.1 g/cm3 (25 ºC)
47 - 49 ºC
304 - 306 ºC
2
4
R 50/53 (Very toxic to
aquatic organisms, may
cause long-term adverse
effects in the aquatic
environment)
S 61 (Avoid release to
the environment. Refer
to special instructions /
Safety data sheets)
Synthesis of Triphenylmethanol
by Markus Arnoldini
NaSO4 [1]
molar weight
density
melting point
boiling point
refraction index
WGK
GK (CH)
R-phrases
S-phrases
NaSO4
142.04 g/mol
2.70 g/cm3 (20 ºC)
888 ºC
1
5
-
Hydrochloric Acid (conc.) [1]
molar weight
density
melting point
boiling point
refraction index
WGK
GK (CH)
R-phrases
HCl
S-phrases
36.46 g/mol
~ 1.19 g/cm3 (20 ºC)
1
2
R 34 (causes burns)
R 36 (irritates eyes)
R 37 (irritates respiratory
system)
R 38 (irritates skin)
S 26 (in case of contact
with eyes rinse with a lot
of water and seek medical
help)
Phenylbromide [1]
Br
molar weight
density
melting point
boiling point
refraction index
WGK
GK (CH)
R-phrases
157.02 g/mol
1.49 g/cm3 (20 ºC)
-31 ºC
156 ºC
2
3
R 10 (Flammable)
R 38 (Irritating to skin)
R 51/53 (Toxic to aquatic
organisms, may cause
long-term adverse effects
in aquatic environments)
S-phrases
S 61 (Avoid release to the
environment. Refer to
special instructions /
Safety data sheets)
6
Synthesis of Triphenylmethanol
by Markus Arnoldini
Triphenylmethanol [1]
OH
molar weight
density
melting point
boiling point
refraction index
WGK
GK (CH)
R-phrases
S-phrases
5.
260.34 g/mol
160-163 °C
360 ºC
-
Experimental accomplishment
0.9 g of magnesium slivers, one I2 crystal and 20 mL of anhydrous Et2O were put in a
250 ml three-neck round bottom flask with a reflux cooler and a dropping funnel. A
solution of 3.5 mL (5.215 g = 0.03 mol) of phenylbromide in 40 mL of anhydrous
Et2O was put into the dropping funnel. Then 5-7 mL of the PhBr solution were added
dropwisely while stirring. Because nothing happened first, the flask was heated in a
water bath to 35 °C and the ether started boiling. At that point the bath was removed.
The remaining PhBr solution was added dropwisely and after that the flask was
heated again with a water bath to around 35 °C for 15 min. While the flask was
heated, a solution made of 4.3 g of benzophenone in 40 mL of anhydrous Et2O was
prepared and put into the dropping funnel. After the aforesaid 15 min the solution was
added slowly to the reaction mixture, was kept another 5 min at 35 °C and was then
cooled down to room temperature. At this point a 6 M solution of HCl was added
drop by drop until a pH of about 1 was reached. The mixture was then put in a
extraction funnel and the two phases were separated. The water phase was then
washed two times with 50 mL of hexane and after every washing step the organic
phase was collected together with the organic phase of the very first separation. The
collected organic phases were then washed with saturated solutions of NaHCO3 and
NaCl and then dried over NaSO4. The Et2O was then removed with a rotovap, and the
resulting solid was dissolved in Et2O and purified by column chromatography. An
amount of 6.4 g (0.024 mol) of product was received.
For the calculation of the yield the molar amount of received product was
divided by the molar amount of reactants used, and then multiplied by 100. This
calculation yields a percentage of 80 %:
0.024mol
 100%  80%
0.03mol
7
Synthesis of Triphenylmethanol
6.
by Markus Arnoldini
Experimental setup
Calciumchloride duct
Reflux-cooler
Thermometer
drop flask
three-neck round bottom flask
LaboB ib©
300
50
AN
AN
AUS
AUS
1500
0 U/min
250
100
o
500
C
200
150
1000
750
Seperatory funnel
600
Beaker to collect water phase
800 mL
400
200
8
Synthesis of Triphenylmethanol
7.
by Markus Arnoldini
Analytical results
The chromatography yielded two different fractions of product, but the measurement
of melting points and IR-spectra indicated that the second fraction was the dimer
product.
Melting point:
156 – 160 °C
Peaks in IR Spectrum (in cm-1):
3300-3600:
3000-3100:
~1600:
970-1050:
OH
CH (aromatic)
aromatic ring
C-O
8.
Sources
[1]
[2]
http://ch.chemdat.info/mda/ch/de/
meanings of R-phrases:
http://www.chemie.fu-berlin.de/chemistry/safety/r-saetze_en.html
meanings of S-phrases:
http://www.chemie.fu-berlin.de/chemistry/safety/s-saetze_en.html
[3]
9