The Preparation Of Organic Compounds

– Aspirins And Oil Of Wintergreen Essay, Research Paper

Title of Experiment: The Preparation of Organic Compounds – Aspirins and Oil of Wintergreen

Introduction

The purpose of this experiment is to prepare two organic compounds (aspirin and oil of wintergreen) and to illustrate the typical organic reactions. Students will also learn some techniques commonly used in organic synthesis and the meaning of the terms theoretical yield, actual yield, and percent yield.

Both Aspirin (acetylsalicylic acid) and oil of wintergreen (methyl salicylate) are commonly used organic compounds. Aspirin is usually used as a pain reliever or fever reducer, and oil of wintergreen is used in rubbing liniments for sore muscles and as a flavoring agent.

Aspirin is usually made by reacting salicylic acid with acetic anhydride.

C7H6O3 + C4H6O3  C9H8O4 + C2H4O2

(salicylic acid) (acetic anhydride) (acetyl salicylic acid: aspirin) (acetic acid)

Oil of wintergreen is made by reacting salicylic acid with methanol in the presence of sulfuric acid.

C7H6O3 + CH4O  C8H8O4 + H2O

(salicylic acid) (methanol) (methyl salicylate: oil of wintergreen) (water)

Procedure

Preparation of Aspirin

1. Set up a water bath and an ice bath.

2. Put 3 grams of salicylic acid and 4mL of acetic anhydride in 125mL conical flask.

3. While swirling the flask, add 5 drops of concentrated sulfuric acid to the mixture.

4. Heat the flask in the beaker of boiling water for 15 minutes or until the solid dissolves.

5. Carefully remove the flask with 9” tongs from the water bath and add 25mL of your ice-cold water to the flask.

6. Set the flask in the ice bath until crystallization appears to be complete.

7. Separate the crystals from the liquid by suction filtration.

8. Rinse the product with ice water to transfer all of the solid aspirin onto the filter paper.

9. Draw air through the product for several minutes.

10. Transfer the solid from the funnel to a preweighed, labeled, dry paper towel, and allow it to dry thoroughly.

11. Make a tablet of aspirin by using a pellet press.

Preparation of Oil of Wintergreen

1. Put about 0.2 grams of salicylic acid and 2mL of methanol in a medium sized test tube and swirl until the solid dissolves.

2. Add 5 drops of concentrated sulfuric acid.

3. Place the test tube in a hot water bath at 60 – 70?C for 15 minutes.

4. Remove the test tube from the hot water bath and let it cool to room temperature.

5. Cautiously smell the contents of the test tube.