Synthesis of Isopentene

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Synthesis of Isopentyl Acetate (Banana Oil) Using A Fischer Esterification Reaction

Purpose: The purpose of this experiment is to synthesize Isopentyl Acetate using a Fischer esterification reaction. Fischer esterification is an acid-catalyzed condensation of an alcohol and a carboxylic acid, yielding an ester and water. Isopentyl Acetate has the scent of banana oil, once synthesized it will be purified by distillation. Then the analysis of the sample using H NMR and IR will determine purity of the product. Reaction Scheme:

Mechanism: Fischer esterification is the acid catalyzed condensation of an alcohol and a carboxylic acid, where it is protonated at the carbonyl oxygen, then the nucleophillic attack of the alcohol. The proton is loss and then regained, followed by a decrease of water as electrons from the alcohol oxygen form the double bond. Finally, the loss of a proton yields the ester.

Procedure: The procedure is outlined in “--”, Seventh Edition, --, Thomson Custom Publishing, Mason Ohio, 2007, pp. 30. Calcium Chloride (CaCl2) was used instead of Magnesium Sulfate (MgSO4) as a drying agent. Boiling stones were used instead of the stir bar. Reagent/Product Table:

Reagents/Product Table: *=measured values +=calculated values
Acetic AcidIsopentyl AlcoholIsopentyl AcetateSulfuric Acid 1Molecular Weight (g/mol)60.052488.1492130.186498.0734 Grams (g)+8.91*53.852.208
Volume (mL)*8.5+6.15+5.54*1.2
1Density (g/mL)1.04920.08131.4041.84
1Boiling pt (⁰C)117.9130142280
1Melting pt (⁰C)16.6111-78.53
1Solubilitymiscible in H2Osolublesolublesoluble
2HazardsCorrosive and flammable; do not contact with skin; or inhaleFlammable; causes coughingFlammable, avoid contact with skin & eyes; irritationcorrosive 2Appearancecolorless/clearcolorless/clearclearclear


Observations: After adding isopentyl alcohol to acetic acid in a round-bottomed flask, the mixture was initially clear and colorless and then turned a tea-like brown tint. Approximately ten minutes into the reflux period a condensation reflux ring was visible near the top of the round-bottom flask and then progressed up the approximately one-third of the condenser column length approximately twenty minutes into the reflux. Thirty minutes into the reflux, the mixture changed to a dark purple color while it bubbled and boiled. This color remained through the extractions but was left in the boiling flask during distillation. Reflux continued for a total of 60 minutes after the reflux ring formed and took approximately ten minutes to cool down to room temperature. Then the room temperature mixture was prepared for extraction with 10mL of water but discovered to be still very acidic after one wash. To reach a neutral pH, it took three washes with Sodium Bicarbonate (NaHCO3) to remove any excess acetic acid and catalytic sulfuric acid. During distillation, the first drop was observed at 135 C and stopped at approximately 139 C when the distilling flask approached dryness. The final product was clear and colorless with a strong scent of bananas. The mass of the product was a 4.42g yield.


Theoretical YieldActual YieldPercent YieldTemp of 1st DropBpt Range Measured/LiteratureAppearance
139/141Clear and colorless

Theoretical Yield: 5.0g x (1mol Isopentyl Alcohol/88.1492g of Isopentyl Alcohol) x (1 mol Isopentyl Acetate/1 mol Isopentyl Alcohol) x ( 130.864g /1 mol Isopentyl Acetate) = 7.42g Mass of Beakers with Product: 26.53

Mass of Beaker: 22.11
Actual Yield = 26.53 – 22.11 = 4.42g

NMR Spectroscopy for Isopentyl Acetate: 200MHz, CDCl3
Protons, HxChemical Shift
(ppm)Splitting PatternIntegration
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