University:
Augusta University
Course:
CHEM 1441 | General Chemistry
Academic year:

2019
Views:

279

Pages:

3
Author:

Arely A

Experiment: 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 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. 1 mol 0.914 g × 1 mL 114.2 g ¿ 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 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.