Purpose
Illustrate the variety of odors that are produced from esters.

Materials

• Organic alcohols in dropper bottles (see chart below)
• Organic acids in dropper bottles (see chart below)
• Sulfuric acid, H2SO4 (18 M)
• Sodium carbonate, Na2CO3
• Test tubes
• Test tube holder
• Bunsen burner
• or, the Ester Formation Lab Activity

Safety

• Read the MSDS/WHMIS sheets for all chemicals before using them
• Wear chemical safety glasses
• Waft vapors when detecting odors
• Concentrated acids are used

Procedure

1. In a test tube add 15 drops of ethanol to 20 drops of glacial acetic acid.
2. Add one drop of concentrated sulfuric acid.
3. Mix the reactants by gently tapping the test tube.
4. Gently heat the bottom of the test tube for several minutes. Keeping the test tube on a slight angle helps control vapor loss. If the solution starts to boil remove it from the heat.
5. Add a small amount of sodium carbonate to neutralize any excess acid.
6. Carefully smell by wafting. Dilute with water if the smell is to strong.
7. See the chart for more combinations. Use 0.5 g of solid acids such as salicylic acid.

Results
Vary depending on the organic acid and alcohol used (see reference chart below).

Follow-up Teaching Notes:

Ester reference chart

• The concentrated sulfuric acid acts a catalyst and as a dehydrating agent for the condensation reaction between the alcohol and the carboxylic acid.
• When using butyric acid perform the demonstration in a fume hood due to the bad butyric acid odor.

Connections
Organic synthesis, esters, condensation reactions.

Disposal/Clean-up
Dispose of the esters down the drain with lots of water. Check local codes before any disposal activity.

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