This lesson submitted by amysev
Chemistry Name ___________________________
Preparation of Fragrant Esters Period ______ Score ____
Thought Question: What determines the way something smells?
Esters are a class of organic compounds that have characteristic sweet and fruity smells. An ester contains a carboxyl group. Today you will be making various types of esters by changing the identity of the “R” group on either side of the carboxyl group.
- Draw the general structural formula for an ester:
Testable Question: Will changing the shape (i.e. structural formula) of an ester change its fragrance?
- 9 test tubes
- Test tube clamp
- Hot plate
- 400 mL beaker
- Methanol, ethanol and 1-pentanol
- Acetic acid, salicylic acid and anthranilic acid
Follow these directions carefully! Do not add more material than is listed.
- Make a 4 x 4 table in your lab notebook that takes up the entire page
- Leave the top left box open name and draw the structural formulas for the alcohols we are using in this experiment in the remaining boxes in the top row
- In the left hand column, draw the names and structures for the carboxylic acids we are using in this experiment (Leave the top right box open)
- Number the boxes 1-9 and draw the appropriate structure and name…leave space to describe the smell.
- Label the test tubes with masking tape and number them 1 thru 9.
- Add 2 mL of alcohol to the appropriate test tubes.
- Add a spatula tip full of each acid to the appropriate test tubes.
- Carefully add 8 drops of sulfuric acid to each test tube.
- Warm the test tubes in a beaker of hot water (60 ºC) for 10 minutes.
- Cool the test tubes in an ice bath.
- Waft the aroma towards your nose with your hand, CAREFULLY!!!
- Record the results under Aroma. Try to relate each odor to a familiar odor of a fruit, flower, or vegetable.
- Was your hypothesis confirmed? Why or why not?
- Why do you think the shape of a molecule affects its odor? Discuss in 3-4 sentences.
TUBE ALCOHOL ACID ESTER FRAGRANCE
1 ethyl alcohol acetic acid fruity
2 methyl alcohol salicylic acid wintergreen
3 ethyl alcohol benzoic acid
4 n-amyl alcohol salicylic acid pineapple (1-pentanol)
5 methyl alcohol anthranilic acid grape (o-aminobenzoic acid)
6 n-amyl alcohol acetic acid banana (1-pentanol)