Lab 5: Preparation of Synthetic Banana Oil
September 20th, 2012
The main purpose of this experiment was to synthesize banana oil (isopentyl acetate.) Ester are often prepared by the Fischer esterification method, which involves heating a carboxylic acid with an alcohol in the presence of an acid catalyst. Theory:
Synthesize isopentyl acetate by combining isopentyl alcohol with acetic acid and sulfuric acid and then heating the reaction mixture under reflux for an hour. The alcohol is the limiting reactant, so it should be weighed/ the acids can be measured by volume. The esterification reaction is reversible, and it has an equilibrium constant of approximately 4.2. A pure component can be obtained from a mixture by separating it from all other components of the mixture, using procedures that take advantage of differences in solubility, boiling points, acid-base properties, and other characteristics of the components. Because isopentyl acetate is a liquid, the separation and purification operations will differ from those used previously for solid products. The water that forms during the reaction will be separated from the ester along with the wash liquids. Any traces of water that remain are then removed by a drying agent, either magnesium sulfate or sodium sulfate. Because isopentyl alcohol has a lower boiling point than that of isopentyl acetate, and the by-products have higher boiling points, it should be possible- in principle- to remove the alcohol and by-products from the ester by distillation. Isopentyl alcohol should distill first, followed by the ester, and any by-products should remain behind in the pot-the vessel in which the reaction mixture is boiled. Reaction:
Acetic acid + isopentyl alcohol isopentyl acetate + water
Weigh 150 mmol of isopentyl alcohol into a round bottom flask of appropriate size, and add boiling chips. Under a hood, add 17 mL of glacial acetic acid, and then carefully mix in 1.0...
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