Organic Chemistry Lab
Dr. Lyn XXXX
2 February 2012
Esterification of Isopentyl Alcohol to Isopentyl Acetate
The technique for esterification that was employed in the experiment was to use a reflux apparatus (Figure 1) while heating in order to evaporate out water to drive our reaction into the product favored direction. The starting material of isopentyl alcohol (1.0 mL) and excess glacial acetic acid(1.5 mL, 17.6M) were eppendorf pipetted into a 5 mL conical vile. This mixture was acid catalyzed by the addition on two drops of H2SO4. The mixture was then heated to 150-160⁰C in order to increase energy for esterification to occur over a period of 60- 75 minutes.
The mixture then was cooled to room temperature before the addition of 5% aqueous sodium bicarbonate( 1.0 mL) in order to react excess acetic acid to form a the anionic form sodium acetate. The reaction separates these anions into the aqueous layer while evolving CO2 as a byproduct. The product was treated three times with sodium bicarbonate in order to be certain that excess glacial acetic acid was removed from the formed isopentyl acetate.
Amount Recovered (mmol)| 5.004 mmol|
Theoretical Yield(g)| 1.196g (Isopentyl Acetate L.R.)|
Actual Yield(g)| 0.6515g|
Percent Recovery| 45.52%|
Appearance of Product| Clear oil. Tint: light gold. |
Figure 2: IR spectrum of recovered esterfication; isopentyl acetate. Relevent peak frequencies include formation of 1743.25 of ester formation. No large abundant peak of alcohol frequencies 3400-320 Discussion
The unique pricnipal demonstrated in this chemical expiramnet was the acid catalyzed ester formation of isopentyl alcohol with excesss glacial acetic acid to drive formation of isopentyl acetate. The reaction was catalzed by two drops H2SO4 to protonate isopentyl alcohol, which significantly increases the carbonyl carbons electrophilicity to react with glacial acetic acid to produce isopentyl...