SYNTHESIS OF ISOAMYL ACETATE FOR AIR FRESHENER APPLICATION

Christian A. Malapit Organic Chemistry Laboratory Department of Chemistry Ateneo de Manila University

Esters are a class of compounds widely distributed in nature. The simple tend to have pleasant odors. In many cases, although not exclusively so, the characteristic and fragrances of flowers and fruits are due to compounds with the functional group. An exception is the case of the essential oils. The odors and flavors of fruits and flowers may often be due to a single ester, but more often, it is due to a complex mixture in which a single ester predominates.

In this experiment, you will prepare an ester, isoamyl acetate (isopentyl acetate). This ester is ofter referred to as banana oil, since it has the familiar odor of this fruit. Isoamyl acetate is used to confer banana in foods. It is also used as a for some and lacquers, as well as being a honey bee pheromone and can be used to attract large groups of honeybees to a small area.

Isoamyl acetate is prepared by the direct acid-catalyzed esterification of with as seen in scheme 1.

Scheme 1. Acid-catalyzed esterification of isoamyl alcohol and acetic acid to form isoamyl acetate.

Procedure

A. Synthesis of isoamyl acetate

In 50 mL round bottom flask, mix 15 mL of isoamyl alcohol, 12 mL glacial acetic acid and 4.0 mL concetrated . Swirl the solution and add boiling chips.

Set-up reflux apparatus and heat the mixture for 20 to 30 minutes. Allow the mixture to cool to room temperature then transfer it in a separatory funnel. Wash the mixture with cold 25 mL of 5 % aqueous sodium bicarbonate solution. Do this 2 to 3 times. Collect the upper layer and dry it over anhydrous sodium sulfate.

Perform hydroxamic acid test and determine the mass and density of the product. Report the % yield of the reaction.

B. Formulation of an air freshener

Prepare an unscented gelatin (carrageenan-based gelatin). The usual preparation is done by dissolving the solid gelatin sample in enough boiling water.

Allow the mixture to cool. Before the solution turns gel, add the synthesized isoamyl acetate (15-20 parts gelatin to 1 part isoamyl acetate by volume). Continue mixing then place the gel in a molder or container.

Package and label the product.

References

Figures can be accessed at: http://en.wikipedia.org/wiki/Isoamyl_acetate or by searching ‘banaba’ and ‘pear’.

Boch R; Shearer DA, Stone BC (September 8, 1962). "Identification of isoamyl acetate as an active component in the sting pheromone of the honey bee.". Nature (England: Nature Publishing Group) 195: 1018–20.