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
3. Mechanism

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
/ MAK: 360 mg/m3, 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 / M = 84.01g/mol
ρ = 2.16g/mLat 25°C / mp = 270°C
/ CH toxicity class: 5
Safety phrases
S24/25: Avoid contact with skin and eyes
Sodium chloride
CAS: 7647-14-5 / M = 58.44g/mol
ρ = 1.37g/mL / bp =1413°C
mp = 801°C
NaCl / CH toxicity class: non-toxic
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
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:

distillation:

6. Amounts of Substance used
Substance / measured amount [ml] / [g] / [mmol] / eq
Isopentyl alcohol / 7.5 / 6.07 / 69 / 1.0
Acetic acid / 10.0 / 10.5 / 175 / 2.5
Sulphuric acid / 2.0 / 3.68 / 38 / 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 125-135 °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] / interpretation
2957
2871 / sat. C-H
1738 / C=O
1465
1387
1365 / CH3

Literature spectrum

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>.