CHEMISTRY CLASS

Synthesis of Fragrant Esters

Bianca Rosas Schulte

Chemistry 115

This experiment is designed to synthesize a variety of esters from a group of carboxylic acids and alcohols. The remaining product with consists of different fragrances that are used in our everyday products, such as Listerine, Gold Bond, toothpaste.

Esterification of a carboxylic acid with an alcohol refers to the simple reaction producing certain smells that are used in fragrances and fruit products. When an acid and an alcohol are combined, then heated, they can give off a fruity smell or a more repellent smell. This dependents on the person’s senses.

Materials

1 Beaker, 100 mL, glass

1 Burner fuel

1 Burner stand

1 Digital scale

1 Pair of safety gloves

1 Pair of safety goggles

4 Test tubes, 13 x 100 mm

1 Test tube holder

1 Test tube cleaning brush

1 Test tube rack, 6 x 13mm

1 Weighing boat, plastic

1 - Methanol, 2 mL in dropper bottle

1 - Ethanol, denatured, 2 mL in dropper bottle

1 - Isoamyl alcohol, 2 mL in glass vial

1 - Acetic acid, 2 mL in dropper bottle

1 - Butyric acid, 2 mL in glass vial

1 - Sulfuric acid, 6M 1 mL in dropper bottle

1 - Salicylic acid, 0.5g in centrifuge tube

1 Aluminum pie plate, disposable

1 Bottle of distilled water

1 Dish soap

1 Matches or lighter

1 Oven mitt or dish towel

1 Roll of paper towels

1 Watch or kitchen timer

1. Put on your safety gloves and goggles.

Part 1

1. Mark three small test tubes with the numbers “1”, “2”, and “3”.

2. Place the test tubes in a rack or well plate to securely hold them while you perform the

experiment

3. Place 4 drops of acetic acid into each numbered test tube.

4. Place 5 drops of methanol into test tube #1.

5. Place 5 drops of ethanol into test tube #2.

6. Place 5 drops of isoamyl alcohol into test tube #3.

7. Add 2 drops of sulfuric acid to each test tube.

8. Gently swirl, shake, and agitate each test tube to mix the acids and alcohols.

9. Fill the 100-mL glass beaker with approximately 50 mL of very hot tap water.

10. Place the burner stand on the aluminum pie plate and place the beaker with the water on top of the burner stand.

Note: Use an oven mitt or dish towel as necessary to carefully transfer the beaker of hot water to the burner stand.

11. Place the burner fuel on the pie plate. Uncap the burner fuel and light the wick with matches

or a lighter.

12. Carefully slide the burner fuel under the stand.

13. After the water has begun to vigorously boil, extinguish the flame by carefully placing the cap over the flame. The water will remain hot long enough for the esterification reaction to takeplace.

14. Use an oven mitt or dish towel to transfer the beaker of hot water from the burner stand to

your work area.

15. Place the 3 test tubes with the acid-alcohol mixtures into the beaker of hot water and let

them stand in the hot water for 5 minutes.

16. Use the test tube clamp to remove the test tubes, 1 at a time, from the hot water bath, placing

them back into the test tube rack. Suck water up into an empty pipet and then add 20 drops

of water from the pipet into each test tube’s contents. Agitate each tube to mix the contents

of the tubes.

17. Cautiously try to detect the odor of the products in each test tube by using your hand to

waft the scent from the test tube toward your nose. Do this until you can detect and record

an odor. Do not worry about having the “correct” odor for a particular ester. Descriptions of

odors often vary with people, and some odors are hard to describe. Record the scents for

each of the test tubes in Data Table 1.

18. Flush the content of the test tubes down the drain with lots of water. Wash the test tubes with

the test tube brush, rinse with distilled water, and dry for use in Part II.

Part 2

1. Mark four small test tubes with the numbers “4”, “5”, “6” and “7”.

2. Place the test tubes in a rack or well plate to securely hold them while you perform the

experiment

3. Perform the following steps near an open window, as butyric acid has a strong, unpleasant

odor like rancid butter.

4. Place 4 drops of butyric acid into test tubes 4, 5 and 6.

5. Place 5 drops of methanol into test tube #4.

6. Place 5 drops of ethanol into test tube #5.

7. Place 5 drops of isoamyl alcohol into test tube #6.

8. Add 2 drops of sulfuric acid to each test tube.

9. Gently agitate each test tube to mix the acids and alcohols.

10. Place the weighing boat on the digital scale and tare the scale so that it reads 0.0 g. Carefully measure 0.2 grams of salicylic acid and transfer it into dry test tube # 7.

11. Add 6 drops of methanol to test tube #7 and agitate the tube until the contents are well

mixed.

12. Add 2 drops of concentrated sulfuric acid into test tube #7, agitate, and return to the test tube

holder.

13. Fill the 100-mL glass beaker with approximately 50 mL of very hot tap water.

14. Place the burner stand on the aluminum pie plate and place the beaker with the water on top

of the burner stand.

Note: Use an oven mitt or dish towel as necessary to carefully transfer the beaker of hot water to the

burner stand.

15. Place the burner fuel on the pie plate. Uncap the burner fuel and light the wick with matches

or a lighter.

16. Carefully slide the burner fuel under the stand.

17. After the water has begun to vigorously boil, extinguish the flame by carefully placing the cap

over the flame. The water will remain hot long enough for the esterification reaction to take

place.

Note: Do NOT tighten the cap until the burner fuel has completely cooled or you may create a

vacuum that will make the fuel very difficult to open in the future.

18. Use an oven mitt or dish towel to transfer the beaker of hot water from the burner stand to

your work area.

19. Place the 3 test tubes with the acid-alcohol mixtures into the beaker of hot water and let

them stand in hot water for 5 minutes.

20. Use a clamp to remove the test tubes, 1 at a time, from the hot water bath and place them

into the test tube rack. Suck water up into an empty pipet and then add 20 drops of water

from the pipet into each test tube’s contents. Agitate each tube to mix the contents of the

tubes.

21. Cautiously try to detect the odor of the products in each test tube by using your hand to

waft the scent from the test tube toward your nose. Do this until you can detect and record

an odor. Do not worry about having the “correct” odor for a particular ester. Descriptions of

odors often vary with people, and some odors are hard to describe. Record the scents for

each of the test tubes in Data Table 1.

22. Flush the contents of the test tubes down the drain with lots of water. Wash the test tubes

with the test tube brush, rinse with distilled water, and dry.

23. Return all items to the kit for future use.

Bianca Rosas Schulte

Week 5 lab

Synthesis of Fragrant Esters

Hands-On Labs, Inc. Version 42-0203-00-02

Lab Report Assistant

This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor.

Exercise 1: Synthesis of Fragrant Esters

Data Table 1. Fragrant Esters.

Tube #	Alcohol	Acid	Common Name	IUPAC Name	Fragrance
1	Methanol	acetic	Methyl acetate	Methyl acetate	Rubber
2	Ethanol	acetic	Ethyl acetate	Ethyl acetate	Fruity
3	Isoamyl*	acetic	isopentyl acetate	3-methylbut-1-yl ethanoate	Paint
4	Methanol	butyric	methyl butanoate	Methyl butanoate	Nail polish
5	Ethanol	butyric	ethyl butanoate	Ethyl butanoate	Fruity
6	Isoamyl*	butyric	Isoamyl butyrate	3-methylbutyl butanoate	Citrus
7	Methanol	salicylic	Methyl Salicylate	Methyl 2-hydroxy-benzoate	No smell

Questions

A. What role does sulfuric acid play in the production of the esters in lab?

An ester is an organic compound that is formed when a carboxylic acid reacts with an alcohol wjile in the presence of a strong mineral acid such as sulfonic acid acting as a catalyst.

B. Name two commercial products that contain oil of wintergreen.

Listerene and Gold Bond

C. Explain why the esters made in this lab could not be used as flavoring agents.

They could not be used as flavoring agents because they are often found in perfumes and essential oils.

D. What would be the name of the ester produced from isoamyl alcohol and isovaleric acid?

3-methyl butyl 3-methyl butanoate