Dehydration of Cyclohexanol The E1 Elimination Reaction PDF

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Summary

This is a post lab report about a dehydration reaction of Cyclohexanol. It is an E1 elimination reaction....

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Emily Schmalzried Cheyenne Hamilton 06.28.2021, CHEM 3105-304 Wahiduzzaman Dehydration of Cyclohexanol: The E1 Elimination Reaction Purpose The purpose of this experiment is to synthesize, purify and analyze the dehydrated cyclohexanol. Reaction and Physical Properties Table

Compounds and Reagents

MW (g/mol)

Amount

cyclohexanol

100.16

H3PO4

mmol

Boiling Point

Density (g/mL)

8 mL

162

0.96

97.99

2.5 mL

158

1.88

H2SO4

98.08

5-8 drops

337

1.84

cyclohexene

82.14

83

0.81

Safety ● Cyclohexanol -

Risks: a. Combustible liquid and gas b. May cause eye or skin irritation

c. May cause respiratory irritation -

Safety: a. Wear protective clothing b. Keep away from flames, heat, etc. c. Do not breathe in fumes, vapors, etc.

● Phosphoric Acid -

Risks: a. May be corrosive to metals b. Causes severe burns and eye damage

-

Safety: a. Wash skin after handling b. Do not breathe in vapors, fumes, etc. c. Keep in original container

● Sulfuric Acid -

Risks: a. May be corrosive to metals b. Causes severe burns and eye damage c. May cause respiratory irritation

-

Safety: a. Do not breathe in vapors, fumes, etc. b. Wash skin after handling c. Use in a well ventilated area

● Bromine Dichloromethane Solution

-

Risks: a. Causes severe skin burns and eye damage b. Fatal if inhaled

-

Safety: a. Do not breathe in vapors, fumes, etc. b. Wash skin after handling

● Cyclohexene -

Risks: a. Highly flammable liquid and vapor b. Harmful if swallowed c. May be fatal if swallowed

-

Safety: a. Wash skin after handling b. Keep away from heat, flames, etc. c. Keep container tightly closed

Procedure ● Synthesis and Purification of Cyclohexane 1. Set up a simple distillation structure in the hood. Heat a hotplate to 350 degrees Celsius. Place the receiving flask in an ice bath. 2. Add 8 mL of cyclohexanol and a boiling stone to a round bottom flask. The TA will add 2.5 mL of 85% phosphoric acid followed by 5-8 drops of H2SO4. 3. Distill until there is 2-3 mL of liquid remains. Transfer the solution to a separatory funnel. 4. Add 3 mL of Na2CO3. Swirl and vent.

5. Drain the bottom layer and test the pH. If not acidic, repeat step 3. 6. Add 3 mL of brine. Drain the bottom layer and the top layer into separate containers. 7. Dry the top layer with a small amount of MgSO4 until it no longer clumps when stirred. 8. Put the dried solution into a round bottom flask and distill it in the structure from the original distillation. 9. Obtain an IR spectrum of the liquid. ● Qualitative Determination of an Alkene 1. Add four drops of cyclohexanol to one vial. 2. Add four drops of the product solution to another vial. 3. To each vial, add 2-3 drops of bromine in dichloromethane. ● Clean-up 1. Add dilute sodium carbonate to the original flask slowly. 2. Transfer the resulting solution to the acid or base waste depending on its pH. 3. Rinse the distillation structure with acetone, then pour it into the non-halogenated waste. Data and Observations The cyclohexene solution we made remained red after adding the bromine solution.

Conclusion and Results

The IR spectrum of our solution doesn’t seem to have any similarities to the cyclohexene IR spectrum. Ours has a broad beal at ~3400, while the cyclohexene has a peak at ~2900. This experiment was important because it showed how to synthesize a dehydrated cyclohexanol, as well as how to purify and analyze it. Overall, it was successful because we performed an E1 elimination reaction, and synthesized a cyclohexene, and obtained an IR spectrum of it. However, it doesn’t seem like our cyclohexanol successfully converted into a cyclohexene.

Post-Lab Questions 1. Which of the following alcohols will undergo dehydration most readily when treated with sulfuric acid? Explain why.

a. The third compound will result in the most stable carbocation when reacting with sulfuric acid, therefore it more readily undergoes dehydration. This is because the third compound is a tertiary alcohol, which results in a tertiary intermediate which is the most stable. 2. What is the E1 product of the following compound?

3. What are the elimination products of the following reaction? Which of the products is the major elimination product?

4. What is the product of the following reaction? Hint: This is a SN1 reaction....