Preparation Of Esters Lab PDF

Preview

Summary

Download Preparation Of Esters Lab PDF

Description



SCH4U: Preparation of Esters Lab

Anil Kumar

Preparation Of Esters

Figure 1: h ttps://blog.trulux.com.au/blog/2015/11/29/esters/

Shreya Anil Kumar Lab Partners: Sandra Ly, Somaya Aziz Mr. Hathaway SCH4U April 3rd  , 2019

1



SCH4U: Preparation of Esters Lab

Anil Kumar

Purpose: To produce an ester using butanoic acid and ethanol through a condensation reaction. Hypothesis: I hypothesize that when butanoic acid (a carboxylic acid) and ethanol (a alcohol) is mixed, the products will be ethyl butanoate (the ester) and water (product formed due to esterification). Ethyl butanoate is also known as “ethyl butyrate, or butyric ether, is an ester with the chemical formula CH3CH2CH2COOCH2CH3, with one oxygen having a double bond” (PubChem, 2019). In conclusion, I hypothesize that the end product of this reaction which is ethyl butanoate will have a pineapple-like odor, meaning this ester is found within pineapples (Britannica, 2015). Observations: Preparation Of Ester: Before and After Observations Ethanol

Appearance

Odor

- Transparent - Liquid - Colourless - Alcohol beverage scent - Potent

Butanoic Acid

Ethyl Butanoate (After 20mins - 48hrs)

- Transparent - Liquid - Colourless

- Transparent - Cloudy/Foggy - Colourless Liquid

- Parmesan cheese scent - Potent - Pungent

- Pineapple scent - Fruity Scent - Freezie-like scent - Pungent

Analysis: Looking back at the observations, before the sulfuric acid and heat was used to catalyze the reaction, the butanoic acid + ethanol solution, appeared to be a clear transparent liquid, with a strong parmesan cheese odour. After 20 minutes the appearance of the reaction product which is

2

SCH4U: Preparation of Esters Lab



Anil Kumar

ethyl butanoate appeared to have a slight yellow tinged liquid with a pineapple-like scent. When comparing our analysis and the after the time frame (20 minutes & 48 hours) observations, it is clearly seen that the correct products were produced from the reactants. In addition, to confirm that a ester was actually created, prior to the lab it is known that, “carboxylic acid esters mostly are colourless, volatile liquids with pleasant odours, and slightly soluble in water” (Britannica, 2015). Taking a look at the observation, the final product was colourless liquid with a pleasant odour of pineapple (fruity scent). In order, to make sure this reaction does not reverse, sulfuric acid (catalyst) was used, and heat was used to catalyze the reaction.

Figure 2: h ttps://www.chegg.com/homework-help/questions-and-answers/acid-oh-ho-ethanol-alcohol-butanoic-acid-carboxylic-acid-ethyl-butanoate-ester-pine apple-q23440432 

Results: In this lab, the result when mixing butanoic acid and ethanol with the aid of a catalyst which is sulfuric acid, it produces an ester through the process of esterification and will also produce a byproduct of water. The ester that is

3

SCH4U: Preparation of Esters Lab



Anil Kumar

produced when butanoic acid and ethanol mix is ethyl butanoate. Ethyl butanoate contains a pleasant fruity scent. Ethanol has a molecular formula of C2H5OH and butanoic acid has a formula of C3H7CO2H. The final product which is ethyl butanoate has molecular formula of C3H7CO2C2H5. During this reaction the hydroxyl group in butanoic acid and a hydrogen atom from ethanol will be removed forming water, which is a byproduct of the condensation reaction that occured. After the condensation reaction, the other two compounds will join, the electrons from oxygen (in ethanol) and carbon (in butanoic acid) atoms will bond. When these electrons join they create a sigma bond, bonding the two compounds and will form the final product, that is ethyl butanoate (the ester). Discussion: When comparing the hypothesis and the final results for this lab, the hypothesis made was precise. It was hypothesized that when butanoic acid and ethanol react, a esterification reaction will occur creating an ester in this case the ester was Ethyl butanoate. After conducting some research we hypothesized that the final product should have pineapple/fruit like odor. After the reaction occurred, and after the time frame of 48 hours, the final product did indeed possess a pineapple/fruit like odor. Overall, the lab was carried out very well, with no visible errors. The hypothesis made from research through external sources and the final results were very much alike, meaning the lab was conducted precisely. However, there are possibilities of many potential errors that could have occured an altered the results of this reaction between butanoic acid and ethanol. Firstly, if the stoichiometric ratios made for the reactions had slight errors, perhaps the wrong amount of butanoic acid and ethanol might have changed the end products or the reaction would easily be

4

SCH4U: Preparation of Esters Lab



Anil Kumar

reversed. Another error that could affect the results, would be that the test tube used was not completely cleaned and unknown residues from previous labs, are still present in the test tube. Causing other unknown reactions between the unknown residues, butanoic acid, and ethanol, which will alter the end products. An important potential error that should be noted is how an individual's nose can sense different scents and everyone’s “smell spectrum” is unique and different. Thus, this could have led to incorrect odour identification. Lastly, due to instrument limitations, it was required to use a DIY condenser tube, and due to this it is possible that some of the vapour molecules escaped, leaving the results slightly inaccurate. There is scope for improvements for this lab based on the variety of potential errors that could have occured. Firstly, to make sure that the test tubes are completely clean, it is recommended to clean with soap and rinse with water to be certain that the test tubes are residue free. An improvement for making sure the stoichiometric ratios are correct, you can double check with another person so they can catch any mistake which perhaps was made. In order, to make sure the smell of the product is not identified incorrectly, group members can all smell the product and compare the scents they smelt and can re-smell the product to verify which scent seems the most prominent. .Lastly, for the instrument limitation error, the best way to rectify this error is to use an actual condenser tube for the most accurate results. Conclusion: In conclusion, a ester was created using butanoic acid and ethanol through a condensation reaction process called esterification. The experimental results stated that the ester created has a pineapple/fruit-like smell, and the final products produced were ethyl butanoate and water. Esters can be found in items used on a day to day basis. “Esters are responsible for the fragrance and

5

SCH4U: Preparation of Esters Lab



Anil Kumar

flavour of flowers and fruits: for example, isopentyl acetate is present in bananas, methyl salicylate in wintergreen, and ethyl butanoate in pineapples. These and other volatile esters with characteristic odours are used

in

perfumes,

synthetic flavours, and

cosmetics.

Certain volatile esters are used as solvents for lacquers, paints, and varnishes: for this purpose, large quantities of ethyl acetate and butyl acetate are commercially produced” (Britannica, 2015). To conclude, esters can be found in many things and they help to mimic odours and allows a substance to have a pleasant smell.

6



SCH4U: Preparation of Esters Lab

Anil Kumar

Bibliography Britannica, T. E. (2015). Ester . Retrieved from https://www.britannica.com/science/ester-chemical-compound Chegg. Inc. (2019). Ethyl Butanoate . Retrieved from https://www.chegg.com/homework-help/questions-and-answers/acid-oh-ho-ethanol-alcoh ol-butanoic-acid-carboxylic-acid-ethyl-butanoate-ester-pineapple-q23440432 PubChem. (2019). Ethyl butyrate . Retrieved from https://pubchem.ncbi.nlm.nih.gov/compound/ethyl_butyrate

7...