Lab #2  Synthesis of an Organic Ester      Return
Many foods such as ice cream, candy, syrup and others contain artificial flavours. many of these flavouring additives are esters. An ester is an organic compound that is produced by the dehydration of a water molecule from between a carboxylic acid and an alcohol.
General Reaction:

Esters are named by combining the name of the alcohol first with the name of the carboxylic acid and adding "ate". For example, ethyl alcohol (ethanol) and benzoic acid react to produce ethyl benzoate. Ethyl alcohol and decanoic acid would produce ethyl decanoate. Most esters have a characteristic odour that help to identify them. USE CAUTION WHEN SMELLING PRODUCTS. SULPHURIC ACID FUMES WILL ALSO BE PRESENT.

Example ester possibilities.
       Ester                   Odour                                             Ester                   Odour
Ethyl benzoate            Fruity                                    Ethyl butyrate             Pineapple
Ethyl cinnamate          Peach                                    Ethyl decanoate          Grape
Ethyl hexanoate          Pineapple/Banana                Ethyl isobutyrate        Apple
Isoamyl butyrate        Apricot                                   Isoamyl salicylate       Pineapple
Methyl salicylate        Wintergreen                         Methyl butyrate         Apple/Banana
Methyl propionate     Rum

1. Create a water bath using an electric hot plate and bring the water to a boil. You may wish to heat water with a Bunsen burner first then maintain it with an electric hot plate. Use boiling chips if available to smooth the boiling.

2. Prepare a distillation flask with 5 mL of any alcohol available. Record the alcohol used along with any other information available on the bottle such as formula and molecular mass.

3. From the available carboxylic acids use either 5 mL or 3 grams and add to the alcohol in the distillation flask. Record the formula and molecular mass if available. If not available you will have to look it up in one of the data books.

4. Carefully add 2 mL of conc. sulphuric acid to the distillation flask. Swirl to mix the contents as evenly as possible. Place the distillation flask into the water bath and warm. (Optional: The use of a condensation tube for reflux purposes will greatly improve your results.)

5. Carefully note any changes in the distillation flask.

6. After about 10 minutes of warming remove the distillation flask and allow it to cool until it is safe to smell. Use caution and smell carefully. If there is no detectable odour then return the flask to the water bath for an addition 5 minutes. Once an odour is detected ask the teacher to decide if the reaction is complete.

7. Neutralize the acidic contents with a alkali until neutrality is reached to litmus.

8. After neutrality check for a detectable odour again.

Available Alcohols:
ethanol, isoamyl (pentan-3-ol), n-butanol, pentanol, methanol, propanol, propan-2-ol, sec-butanol, tert-butanol, octanol

Available Carboxylic Acids:
acetic (ethanoic), formic (methanoic), salicylic, butyric, decanoic, hexanoic

Alcohol used:
Mass of alcohol used:
Molecular mass of alcohol:

Carboxylic acid used:
Mass of acid used:
Molecular mass of acid:

Lab report
This lab report is more theoretical than practical since you were not required to weight the final product.

1. Write the complete balanced reaction equation for each combination that you created.

2. Calculate the amount of predicted product ester you should have made from your starting materials.