sch4c esters lab

Steve Hall SCH4C pg 1/8

Examining the Synthesis of Esters

by Steve M. Hall

Ms A. StewartSCH4C

2013-05-08


Introduction:Esters are organic compounds that contain a carbonyl group bonded to an oxygen atom. Esters are formed whena carboxylic acid reacts with an alcohol, resulting in esterification. A carboxylic acid contains the -COOH group, and in an ester, the hydrogen in this group is replaced by a hydrocarbon group of some kind. This could be an alkyl 1 group like methyl or ethyl or one containing a benzyne ring2 like phenyl. Many esters are found naturally in fruits and are responsible for the pleasant fruity odours. Synthetic esters are produced from condensation reactions (esterification) between a carboxylic acid and an alcohol. Esters occur naturally in many plants and provide the odours of fruits and flowers. Esters can be split back into an alcohol and carboxylic acid through a process called hydrolysis which is basically adding water.

A real life application of esterification is taking steroids esterification temporarily deactivates the steroid molecule when taken. The carbon chain on the molecule blocks the androgen receptor, which is supposed to be releasing testosterone. In order for the compound to become active again, the ester must be removed. This occurs when the compound has filtered into the blood circulation and enzymes within our body remove the ester chain. If you have ever taken a pill that's drug name is ___________ (brand name) SR/SA/ER/XR/XL/TR/CR3 these create esterification in your body in order to extend the release of the compound into your system.

Purpose:In this activity, we will synthesize several esters by combining various alcohols with a carboxylic acid. Then we will identify the odours of the esters you have synthesized.

Apparatus: 500 mL beaker hot plate 10mL graduated cylinder 2 test tubes test tube rack marker 10mL graduated pipette Petri dish balance

Materials: water ethanol (CH3CH2OH)4 2-propanol (CH3CH2CH2CH2CH2OH)5 Concentrated acetic acid (CH3COOH)6

Procedure:1. Prepare a boiling water bath by half-filling a 500mL beaker with water and heating the beaker carefully on a hot

plate until the water comes to a gentle boil.

2. Number three test tubes using the marker. Use the graduated cylinder to measure 1mL of a different alcohol into each test tube as indicated in the table below7.

1 A hydrocarbon radical derived from an alkane by removal of a hydrogen atom. A branch. (Wikipedia)2 An organic chemical compound with the molecular formula C6H6. Its molecule is 6 carbon atoms joined in a ring, with1

hydrogen atom attached to each carbon atom.3 See figure 14 See figure 25 See figure 36 See figure 47 See figure 5


(Procedure continued)3. In a fume hood, use a pipette to add 1 mL of concentrated acetic acid and 0.5mL of concentrated sulfuric acid to

each test tube, as indicated in the table below8. Gently shake each test tube to mix the contents. THESE ACIDS ARE CORROSIVE9 SO AVOID CONTACT WITH SKIN AND EYES. AVOID INHALATION!

Contents Test Tube 1 Test Tube 2

Alcohol (1mL) Ethanol 2-propanol

Acid (1mL) Conc. Acetic acid Conc. Acetic acid

Catalyst (0.5mL) Conc. Sulfuric acid Conc. Sulfuric acid

4. Carefully return the test tubes to your lab bench. Place all three test tubes in the hot water bath10. Be careful not to point the test tubes at anybody. After about 5 minutes of heating, remove the test tubes from the heat and put them back in the test tube rack.

5. Pour the contents of the first test tube into a Petri dish that is half filled with cold water11. Identify the odour of the ester, using the wafting technique taught by your teacher12.

6. Repeat Step 5 for each ester.

7. Dispose of the solutions as instructed by your teacher. DO NOT POUR DOWN THE SINK!!

Observations & Data:Reaction 1 Reaction 2

Name of alcohol used

Ethanol 2-propanol

Structural formula of alcohol used

See figure 2 See figure 3

Name of carboxylic acid used

Acetic acid / Ethanoic acid Acetic acid / Ethanoic acid

Structural formula of carboxylic acid used


Name of ester produced

Ethyl ethanoate Propyl ethanoate

Structural formula of ester produced


Odour of ester produced

Burning rubber / tires Apo-Cephalex13, an antibiotic received on prescription.

8 See figure 69 See figure 710 See figure 811 See figure 912 See figure 1013 See figure 14


Results & Discussion:1. Complete the table and attach to lab report.

Answer: See Observations & Data

2. Draw the structural formula equations to represent the two esterification reactions in this activity.Answer: See Figure 12 and Figure 13

3. What is the role of the sulfuric acid? Is it included in the equation of the reactions? Answer: The role of the sulfuric acid is to act as the catalyst. A catalyst is a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change. Catalysis is the increase in rate of a chemical reaction due to the participation of a substance which we call a catalyst. In other words, a catalyst speeds up a reaction that is already going to happen. Since we only had a 75 minute period to complete this lab, we needed to speed up the process of esterification therefore, we used sulfuric acid to do so.

Conclusion:As already covered, esterification is a chemical reaction used for making esters. The reaction involves a carboxylic acid combining with an alcohol. We have discovered in this lab that esters are what make organic materials smell, such as flowers and fruits. However, we have also discovered not all esters smell good. Esterification is a common chemical reaction found in industrial settings and nature.

Works Cited:Benzene. Wikipedia. N.p.: n.p., 2013. Wikipedia. Web. 9 May 2013. .

Bloch, D. R. Organic Chemistry Demystified. New York: McGraw, 2006. Print.

candle25, ed. All About Esters. Anabolic Minds. Crawlability, 23 Jan. 2004. Web. 9 May 2013. .

Chan, Markus. Chemistry 11, University Preparation (SCH3U). Ontario ed. Mississauga: Castle Rock Research, 2008. Print.

Chatwal, G. R. Pharmaceutical Organic Chemistry. Rev. ed. Mumbai [India]: Himalaya Pub., 2010. Print.

Clancy, Christina. McGraw-Hill Ryerson Chemistry 11. Toronto: McGraw, 2010. Print.

Clark, Jim. Introducing Esters. Chemguide. N.p., 2004. Web. 9 May 2013. .

Ester. Wikipedia. Wikipedia, 21 Apr. 2013. Web. 9 May 2013. .

Haberer, Stephen, and Maurice DiGiuseppe. Nelson Chemistry 11: University Preparation. Toronto: Thomson/Nelson, 2011. Print.

Rosenberg, Jerome Laib, Lawrence M. Epstein, and Peter J. Krieger. Schaums Outline of College Chemistry. 9th ed. New York: McGraw, 2007. Print.

Stack-Durward, D., and S. Szkurhan. Hydrocarbons and Energy: SCH3U Grade 11 University Chemistry Guide.

Maitland: Science Teachers Association of Ontario, 2001. Print.

Stewart, Amanda, O.C.T. Carboxylic Acids. SCH4C: n. pag. Print.- - -. Esters. SCH4C: n. pag. Print.- - -. Functional Groups. SCH4C: n. pag. Print.

Time release technology. Wikipedia. N.p.: n.p., 2013. Wikipedia. Web. 9 May 2013. .


Appendices:

Figure 1 Figure 2

Figure 3 Figure 4

Figure 5 Figure 6


(Appendices continued)

Figure 7 Figure 8

Figure 9Figure 10


(Appendices continued)

Figure 11 Figure 12

Figure 13Figure 14


Rubric:You will be creating a formal lab report for this lab to be handed in and evaluated. The lab report should be typed and include the following:

1. Title Page2. Purpose of the lab.3. Materials List4. Procedure5. Table6. Analysis7. Conclusion

Level 1

Level 2

Level 3

Level 4

Understanding of Content - Use of proper terminology- Correct structural formula of the THREE reactions- Correct identification of productsUse of critical thinking processes- Ability to justify conclusions based on the evidence/data gathered- Ability to gather and record data- Ability to determine the odours produced. Expression & Organization of Ideas/Information- Sentences are complete and free of spelling & grammatical errors- Data is organized neatly in a table- Report is typed (except Q#1 and Q#2)- Title page is attached and has all necessary information- Lab Report is divided into subtitles listed above

Overall mark = ___________

sch4c esters lab

Documents