CHM457 LAB REPORT EXP 2 Preparation of 4-methylcyclohexene from dehydration of 4-methylcyclohexanol PDF

Preview

Summary

CHM457 LAB REPORT EXP 2 Preparation of 4-methylcyclohexene from dehydration of 4-methylcyclohexanol...

Description

LABORATORY REPORT

FOR

FUNDAMENTAL ORGANIC CHEMISTRY CHM457

Experiment 2

Details of the student: Name: Matrix no: Lecturer’s name: Submission date:

27 April 2021

Evaluation criteria: Total marks: 20 Marks given: Report ------/15 Skill -----/ 5

CHM457_OCTOBER 2020_ODL LAB ASSESSMENT

Experiment 2: Preparation of 4-methylcyclohexene from dehydration of 4methylcyclohexanol Objectives i.

To synthesize 4-methylcyclohexene from 4-metylcyclohexanol by acid-catalyzed dehydration

Chemicals and apparatus Based on the lab manual: i. List all the chemicals used - 7.5 mL of 4-methylcyclohexanol - 2.0 mL of 85% phosphoric acid - 30 drops (0.40 mL) of concentrated sulphuric acid - Saturated sodium chloride solution - Granular anhydrous sodium - Bromine - Potassium permanganate ii.

Show/Draw simple distillation set up with complete labelling of apparatus

CHM457_OCTOBER 2020_ODL LAB ASSESSMENT

Results and Discussion Weight of cyclohexanol = 7.5 mL Density of cyclohexanol = 0.914 g/mL i.

What is the purpose of the simple distillation? The purpose of the simple distillation is to separate two different liquid with different high boiling point. In this experiment, simple distillation is used to separate 4-methylcyclohexene from 4-methylcyclohexanol.

ii.

What is the role of the condenser in the distillation? The condenser is to allow hot vapour to be cooled and condenses to liquid again. When the liquid being distilled is heated, the liquid in the mixture that have a lower boiling point will form vapour in the condenser. The vapour then will be cooled by a cooler fluid surrounding the condenser, condenses back into liquid and flow out into a receiving flask.

iii.

Why saturated NaCl (brine) is used to wash the distillate (crude 4methylcyclohexene)? It is to remove large amounts of water from the distillate.

iv.

What is the purpose of using anti bumping granules during distillation? The anti-bumping granules provide a nucleation site for the liquid to transition from liquid to gas without it being superheated and splashes around.

v.

Calculate the theoretical mass of the product 4-methylcyclohexene. 0.914 g 1 mol × 114.2 g 1 mL ¿ 0.060 mol

nol=7.5 mL×

1 mol of cyclohexanol produces 1mol cyclohexene ∴0.060 mol of cyclohexanol produced 0.060 mol of cyclohexene

theoretical mass of cyclohexene=0.060 mol × ¿ 5.77 g

CHM457_OCTOBER 2020_ODL LAB ASSESSMENT

96.2 g 1 mol

vi.

Calculate the yield of the product if 4.55 g of 4-methylcyclohexene was produced experimentally. percent yield ( % )=

4.55 g × 100 5.77 g ¿ 78.86 %

vii.

Give the expected observation when alkene is tested with a. Bromine in CCl4 The colour changes from brown to clear b. KMnO4 solution The colour changes from purple to brown

Conclusion: In conclusion, the experiment was successful as 4-methylcyclohexene was extracted from 4methylcyclohexanol. From the results obtained, the theoretical mass of cyclohexene is 5.77 g and the experimental mass is 4.55 g. The percent yield of the product calculated is 78.86%. There are possible error that might prevent the percent yield to be 100%. For instance, sample lost when transferring it from one container to another as some of the samples sticks to the container.

References: Deepak. (2020, December 2). What Is the Purpose of Distillation and Reflux Condenser? Lab-Training.Com. https://lab-training.com/2016/03/02/distillation-and-refluxcondensers/ Distillation. (n.d.). Wired Chemist. Retrieved April 23, 2021, from http://www.wiredchemist.com/chemistry/instructional/laboratorytutorials/distillation#:%7E:text=Simple%20distillation%20is%20a %20procedure,difference%20in%20their%20boiling%20points. Libretexts, & Nichols, L. (2021a, March 5). 1.4B: Controlled Boiling. Chemistry LibreTexts. https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Book %3A_Organic_Chemistry_Lab_Techniques_(Nichols)/01%3A_General_Techniques/ 1.04%3A_Heating_and_Cooling_Methods/1.4B%3A_Controlled_Boiling

CHM457_OCTOBER 2020_ODL LAB ASSESSMENT

Libretexts, & Nichols, L. (2021b, March 5). 4.7: Reaction Work-Ups. Chemistry LibreTexts. https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Book %3A_Organic_Chemistry_Lab_Techniques_(Nichols)/04%3A_Extraction/4.07%3A_ Reaction_Work-Ups Nguyen, D. H. (2019, March 2). What Can Affect Chemistry Results? Sciencing. https://sciencing.com/can-affect-chemistry-results-9153.html O615: Bromination and Oxidation – Alkanes and Alkenes. (2015, December 23). Lecture Demonstration Manual General Chemistry. https://www.colorado.edu/lab/lecturedemo-manual/o615-bromination-and-oxidation-alkanes-and-alkenes Wikipedia contributors. (2021, January 21). Liebig condenser. Wikipedia. https://en.wikipedia.org/wiki/Liebig_condenser#:%7E:text=The%20Liebig %20condenser%20or%20straight,in%20vertical%20or%20oblique%20orientation.

Questions: 1. What major alkene product is produced by the dehydration of the following alcohols? a. Cyclohexanol

Major product: cyclohexene

b. 1-Methylcyclohexanol

Major product: 1-methylcyclohexene

CHM457_OCTOBER 2020_ODL LAB ASSESSMENT

c. 2-Methylcyclohexanol

Major product: 1-methylcyclohexene

d. 2,2-Dimethylcyclohexanol

Major product: 1,2-dimethylcyclohexane

e. 1,2-cyclohexanediol (hint: consider keto-enol tautomerism)

Major product: cyclohexanone

CHM457_OCTOBER 2020_ODL LAB ASSESSMENT...