Esterfication. he purpose of this lab is to achieve a specific odour through the process of esterification where carboxylic acid and alcohol react to produce an ester and water with the assistance of heat and a catalyst such as sulphuric acid.

Apparatus:

        - beaker

        - hot plate

        - thermometer

        -  concentrated H2SO4 

        - alcohol (methanol, ethanol, 1-propanol, 1-butanol, 2-butanol, i-butanol, t-butanol, 1-                     pentanol, i-pentanol and octanol)

        - carboxylic acid (methanoic acid, ethanoic acid, propanoic acid, benzoic acid or salicylic                   acid)

        - glacial acetic acid

        - test tube

        - rubber stopper

        - ice

        - ice crusher

        - gloves

        -water squeeze bottles

        -watch glass

        -test tube

        - organic waste container

        - molecular model kit/ ChemSketch software

Method:

        

        Part 1:

1. Fill a 500 mL beaker with water to prepare a hot water bath and heat it carefully on a hot plate. In hot water bath remains between 60-65°C use a thermometer.
2. Place 2 dropperfulls of the alcohol and 2 dopperfulls of the carboxylic acid in a clean dry test tube. If the carboxylic acid is a solid, then add enough so that the solid in the test tube is 0.5 cm high.
3. Add 5-10 drops of a concentrated form of H2SO4  to the reactants and gently mix by swirling the test tube.
4. Loosely seal the test tube with a rubber stopper and place it in the hot water bath for about 1--15 minutes. Remove the test tube in turn and carefully waft the vapour towards nose. If the odour cannot be detected, pour a small portion of the content into a beaker of crushed ice by noting the odour of the product.
5. Once ester is produced, the teacher is to evaluate it for the desired odour.
6. Upon completion of the reaction, the contents of the test tube are to be discarded in the container labelled as "Organic Waste" which is kept in the fume hood.
7. Clean up by washing all glassware with soap, followed by rinsing 3 times with tap water and drying it with a paper towel.

Part 2:

1. A model of the product (ester) is to be built with either a molecular model kit or the ChemSketch software.

Observations:

Extension Questions:

1. The purpose of H2SO4 in this lab was to be a catalyst in order to speed up the process but it does not undergo a chemical change itself.
2. The odour will be enhanced through the process of pouring it on ice because of the fact that esters are not soluble in water.  Esters are non-polar while water is a polar substance, since "like dissolves in like", they are not soluble in substances other then non-polar. As a result, the carboxylic acid and alcohol will sink and remain at the bottom of the test tube and not dissolve.
3. The alcohol provides the oxygen atoms for the ester. This is because when the carboxylic acid reacts in combination with the alcohol, the hydroxyl from the acid reacts with the alcohols'  hydrogen allowing the formation of water. As a result of this, the alcohol leaves behind oxygen atoms to allow an ester to be able to form.
4. The acid used in order to produce acetylsalicylic acid (aspirin) is acetic anhydride and there is no alcohol used  so instead another acid called salicylic acid is substituted since it consists of the hydroxyl group. The correct ester name for aspirin is  2-acetyloxybenzoic acid.
5. In order to make the oil of the wintergreen odour, the substances salicylic acid and methanol are required in order to  produce the methyl salicylate. However, the difference is the role in which it plays during the reaction since in wintergreen it is substituted as the carboxylic acid but in order to produce aspirin it is used as the alcohol. The substance which is common in both aspirin and wintergreen is the salicylic acid.
6. Fats and oils consist of any form of acid. However, the alcohol remains fairly constant in the form of glycerol or in other words propane -1,2,3- triol. This form of alcohol contains a hydroxyl allowing longer chains to form of carbon.
7. A common commercial use for esters is in the perfume industry where a synthetic scent is created within labs through the process of esterfication. For example, Benzyl Acetate is one form of an ester that can be used as to create a perfume scent.

Experimental Uncertainties:

1. The rubber stopper does not completely cover the surface of the test tube's mouth making it easy for gas to escape during the heating process.
2. The thermometer has an uncertainty because it was limited to 1°C, preventing an accurate reading from the thermometer in order to determine when the hot water bath has reached a temperature of 60-65°C. The temperature of the hot water bath is also difficult to remain constant since it fluctuates once removed from the hot plate.

Conclusion:

                When the benzoic acid reacts with ethanol it produces an ester called ethyl         benzoate and water. This is because in order for esterification to occur, an acid reacts         with an alcohol to produce an ester and water through the use of heat and a catalyst         such as sulphuric acid in order to speed up the process. In order to determine whether         the process is complete factors such as odour, melting point, boiling point and solubility         are to change. The odour of the ester has a pleasant smell, a lower melting and boiling         point and is insoluble in water due to the fact that it is a non-polar compound.