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
Isopentyl Acetate
1. Method
The method for the synthesis of Isopently acetate is an sulphuric acid
catalyzed esterification reaction of Isopentyl alcohol with acetic acid.
2. Reaction Equation
+ H2 SO4
O
+
OH
O
- H2 O
HO
O
3. Mechanism
Esterification Reaction (acid catalyzed)
acidic catalyst
Tautomerization
H
O
+H
O
OH
OH H
+
HO
O
O
O
OH
OH
H
OH
H
- H2 O
H
O
-H
O
O
O
catalyst is retrieved
4. Physical and Chemical Properties of Substances
Isopentyl alcohol
CAS: 123-51-3
M: 88.15 g/mol
d: 0.809 g/mL at 25 °C
bp: 130 °C
mp: -117 °C
n20D: 1.4053
3
MAK: 360 mg/m , 100 mL/m3
CH-toxicity class: 4
Risk Phrases
-R10: Flammable
-R20: Harmful by inhalation
-R37: Irritating to the respiratory system
-R66: Repeated exposure may cause skin
dryness or cracking
Safety Phrases
-S46: If swallowed, seek medical advice
immediately and show this container or label
Acetic acid
CAS: 64-19-7
M: 60.05 g/mol
d: 1.049 g/mL
bp: 117 - 118 °C
mp: 16.2 °C
n20D: 1.3716
MAK: 25 mg/m3, 10 mL/m3
CH-toxicity class: 3
Risk Phrases
-R10: Flammable
-R35: Causes severe burns
Safety Phrases
-S23: Do not breathe gas/fumes/vapor/spray
(appropriate wording to be specified by the
manufacturer)
-S26: In case of contact with eyes, rinse
immediately with plenty of water and seek
medical advice
-S45: In case of accident or if you feel unwell,
seek medical advice immediately (show label
where possible)
Sulfuric acid (96 %)
CAS: 7664-93-9
M: 98.08 g/mol
d: 1.840 g/mL
bp: 330 °C
mp: -15 °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)
Sodium bicarbonate
CAS: 144-55-8
O
+
Na
HO
O
-
Sodium chloride
CAS: 7647-14-5
M = 84.01g/mol
ρ = 2.16 g/mL at 25 °C
CH toxicity class: 5
mp = 270 °C
Safety phrases
S24/25: Avoid contact with skin and eyes
M = 58.44g/mol
bp =1413 °C
ρ = 1.37g/mL
mp = 801 °C
CH toxicity class: non-toxic
NaCl
Safety phrases
S24/25: Avoid contact with skin and eyes
Magnesium sulfate
CAS: 7487-88-9
M = 120.36g/mol
mp = 1124 °C
CH toxicity class: non-toxic
O
2+
Mg
O
-
S
O
O
-
Safety phrases
S22: Do not breathe dust
S24/25: Avoid contact with skin and eyes
Isopentyl acetate
CAS: 123-92-2
M: 130.18 g/mol
d: 0.876 g/mL
bp: 142 °C
mp: -78 °C
n20D: 1.4
MAK: 525 mg/m3, 100 mL/m3
Risk Phrases
-R10: Flammable
-R66: Repeated exposure may cause skin
dryness or cracking
Safety Phrases
-S23: Do not breathe gas/fumes/vapor/spray
(appropriate wording to be specified by the
manufacturer)
-S25: Avoid contact with eyes
5. Experimental Setup
reflux:
washing:
20o
20o
separatory funnel
organic phase
aqueous phase
100
100 mL
NS 14
o
75
20
50
250 mL
LaboBib
300
50
©
AN
AN
AUS
AUS
1500
0 U/min
250
500
100
o
C
200
150
1000
750
-45 o
distillation:
NS 29
75o
NS 29
-75 o
NS 29
75o
out
100 m L
oil bath
in
LaboBib
300
50
©
AN
AN
AUS
AUS
1500
0 U/min
250
100
o
500
C
200
150
1000
750
100
m
L
50 mL
mL
100
6. Amounts of Substance used
Substance
Isopentyl alcohol
Acetic acid
Sulphuric acid
measured
amount [ml]
7.5
10.0
2.0
[g]
[mmol]
eq
6.07
10.5
3.68
69
175
38
1.0
2.5
0.6
7. Experimental Section (Procedure)
7.5 mL (1.0 eq.) Isopentyl alcohol and 10.0 mL (2.5 eq.) Acetic acid are mixed
together in a 50 mL two-neck round bottom flask. The mixture is heated at
reflux at 160 °C for 1h. The color will turn to orange-brown. After the mixture
has cooled down to RT it can be washed once with 15 mL distilled water,
thrice with saturated NaHCO3 (3 x 15 mL) and once with 15 mL saturated
NaCl. It is dried over MgSO4 over night and then filtered.
The crude product is further purified by simple distillation. The fraction of 125135 °C is collected and characterized.
8. Yield
The theoretical yield is 69mmol. The experimental yield is 5.6915 g =
43.72mmol.
The yield percentage therefore is 63.5%
9. Characterization
Refractive index
A refractive index of nD=1.3984 was measured. The literature value for
Isopentyl acetate is n20D =1.4.
IR-Spectrum (see attachement)
bands [cm-1]
2957
2871
1738
1465
1387
1365
Literature spectrum
interpretation
sat. C-H
C=O
CH3
10. Remarks and Discussion
The measured refractive index corresponds well to the literature value and
the yield is relatively high. The IR spectrum however is not perfect; possibly I
put too much substance on the window.
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>.