Abstract Fisher Reaction is a special type of esterification that uses an acid catalyst to reflux Carboxylic acid and Alcohol. The product Ester is in equilibrium to the reactants acid and alcohol. Ester is responsible for the smell and aroma of different fruits. After using the Fisher reaction, a combination of techniques is used to separate the product. Introduction Esters are naturally occurring compounds that possess a distinctive odor. It is responsible for the smell of different fruits such as bananas and strawberries. Esters are most commonly from Carboxylic acids, and Alcohols.
They have a pleasant and fruity odor. Esters may be produced in the laboratory via the Fischer reaction. The objective of this experiment is to be able to prepare the assigned ester by using the Fischer Reaction and to calculate the percent yield. Methodology Materials: Isoamyl Alcohol Acetic Anhydride Concentrated H2SO4 Saturated NaHCO3 NaCl solution Reflux Setup: The reflux setup contains a condensing system at a 90-degree angle with the flasks that prevents the solvent from evaporating but at the same time maintaining the temperature of the solvent.
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The 90-degree angle allows condensed solvent to go back to the reaction pot. PROCEDURE Two dry test tubes labelled A and B containing the required 2. 5 mL isoamyl alcohol and 2. 6 mL acetic anhydride respectively were placed in an ice water bath. Concentrated H2SO4 was cautiously added in test tube B. The solution was mixed well using a dropper. While keeping both tubes in an ice bath, the contents of test tube B was slowly added to test tube A. The tube was swirled constantly. The resulting mixture was transferred in a reflux setup.
Boiling chips were added in the setup and was heated in a water bath at 80 degrees Celsius for 30 minutes. After 30 minutes, the hot bath was removed from the setup. It was cooled for a minute and the contents were poured in a small beaker containing a cube of crushed ice. The resulting mixture was transferred in a separatory funnel containing 15 mL saturated NaHCO3 solution. The funnel was secured using the cap after the bubbles had stopped forming. The separatory funnel was swirled gently to prevent emulsion.
The two layers were allowed to separate. The cap was removed and the lower layer was discarded. The extraction was repeated with another NaHCO3. Next, the mixture was extracted with 15 mL saturated NaCl solution. Then, the organic layer was transferred into a clean, dry beaker with half spatula of anhydrous Na2SO4. Finally, the final product was weighed. The percent yield was calculated. A. Results and Discussion Volume of Isoamyl Alcohol2. 5 mL Volume of Acetic Anhydride2. 6 mL Weight of Empty Vial16. 7572 grams
Weight of Banana Flavor + vial18. 8188 grams Weight of Banana Flavor2. 0616 grams Theoretical Yield2. 99 grams % Yield68. 9 % To calculate for the percent yield: this formula was used: % Yield = actual yield/ theoretical yield X 100% 2. 0616 grams x 100% 2. 99 grams = 68. 9 % In the Fischer Esterification, Sulfuric Acid served as the catalyst in the reaction. It served as a dehydrating agent to lower the water molecules present in the equation. Sodium bicarbonate added in the resulting mixture after reflux served to neutralize the acid.
Saturated NaCl was used to help remove the water which prevents or delays the reaction into completion. Swirling the separatory funnel served to prevent from forming emulsion. The boiling chips were also essential in the experiment because it prevents the container and the solution from overheating. One possible source of error in getting the true percent yield is the presence of water. The water was not completely removed. Another source of error is that inaccuracy of the measurement of the volume and mass. Conclusion
The group was able to prepare the assigned Ester via the Fischer Reaction. The experiment’s product is Ester (Isoamyl Acetate) which is clear and colorless and smells pleasantly beautiful and fragrant. The percent yield of the product produced was 68. 9%. References McMurry, J. (2007). Organic Chemistry: A Biological Approach. Belmont, Ca: Thomson Higher Education Solomons, T. W. Graham. (2011). Organic chemistry. Hoboken, NJ : Wiley. Smith, Janice G. (2011). Organic chemistry. New York, NY : McGraw-Hill, c2011.