Dehydration Of 4-Methylcyclohexanol Essay
DEHYDRATION OF 4-METHYLCYCLOHEXANOL
PURPOSE
Perform an acid-catalyzed dehydration of 4-methylcyclohexanol to produce
4-methycyclohexene.
TECHNIQUES
• Dehydration of an alcohol
• Preparation of an alkene
• Distillation
• Unsaturation tests
THEORY
An acid-catalyzed dehydration is a common way to synthesize an alkene from an alcohol.
Use of a strong acid like sulfuric or phosphoric acid serves to protonate the alcohol "OH" group, forming an H2O molecule that is a much better leaving group. As the water leaves the starting material, a proton is also lost in an elimination process. The end result is the alkene product. The chemical equation that describes this experiment is:
OH
H3PO4
+ H2O
heat
CH3
CH3
This type …show more content…
Use a final rinse of acetone to insure that water is removed. Transfer the dried organic to a clean 50 mL round-bottom (leaving drying agent behind), add a boiling stone, and use this as the boiling flask of a distillation set-up. You should pre-weigh a
25 mL round-bottom and use it as the receiving flask. Cool this receiver in an ice bath since the product alkene is fairly volatile. Perform the distillation and collect the purified
4-methylcyclohexene, leaving behind a small amount of impurity in the boiling flask.
You should record the boiling point range you observed during this process. Reweigh the receiving flask and record the mass of product recovered. Calculate percent yield.
UNSATURATION TESTS
Place 4 or 5 drops of 4-methylcyclohexanol starting material into each of two small labeled test tubes. Take two more small labeled test tubes and place 4 or 5 drops of your
4-methylcyclohexene product in each of them. Take one tube from each group, and count how many drops of the provided bromine in methylene chloride solution it takes before the red color remains upon contact with the liquid sample. Record this information. Test the remaining two liquids in a similar way using the potassium permanganate …show more content…
You may need to refer to a lecture textbook.
2) In the laboratory experiment, as the 4-methycyclohexene and water are being formed, they are constantly being distilled from the reaction mixture into a separate receiving flask. Explain how this process helps the reaction proceed with a higher yield.
3) What major alkene product is produced by dehydration of the following alcohols? You must draw the structure of the reactant alcohol and the final product in each answer.
a) cyclopentanol
b) 1-methylcyclohexanol
c) 2-methylcyclohexanol (Hint: look for a rearrangement and two products)
4) In this experiment, several mL of saturated sodium chloride is used to transfer crude product after the initial distillation. Why is saturated sodium chloride, rather than pure water, used for this procedure?
5) Write the structure of the two products that form when the Baeyer Test is performed on cyclobutene. S '08 M. Hauser (Survival Manual 7e) updated
PURPOSE
Perform an acid-catalyzed dehydration of 4-methylcyclohexanol to produce
4-methycyclohexene.
TECHNIQUES
• Dehydration of an alcohol
• Preparation of an alkene
• Distillation
• Unsaturation tests
THEORY
An acid-catalyzed dehydration is a common way to synthesize an alkene from an alcohol.
Use of a strong acid like sulfuric or phosphoric acid serves to protonate the alcohol "OH" group, forming an H2O molecule that is a much better leaving group. As the water leaves the starting material, a proton is also lost in an elimination process. The end result is the alkene product. The chemical equation that describes this experiment is:
OH
H3PO4
+ H2O
heat
CH3
CH3
This type …show more content…
Use a final rinse of acetone to insure that water is removed. Transfer the dried organic to a clean 50 mL round-bottom (leaving drying agent behind), add a boiling stone, and use this as the boiling flask of a distillation set-up. You should pre-weigh a
25 mL round-bottom and use it as the receiving flask. Cool this receiver in an ice bath since the product alkene is fairly volatile. Perform the distillation and collect the purified
4-methylcyclohexene, leaving behind a small amount of impurity in the boiling flask.
You should record the boiling point range you observed during this process. Reweigh the receiving flask and record the mass of product recovered. Calculate percent yield.
UNSATURATION TESTS
Place 4 or 5 drops of 4-methylcyclohexanol starting material into each of two small labeled test tubes. Take two more small labeled test tubes and place 4 or 5 drops of your
4-methylcyclohexene product in each of them. Take one tube from each group, and count how many drops of the provided bromine in methylene chloride solution it takes before the red color remains upon contact with the liquid sample. Record this information. Test the remaining two liquids in a similar way using the potassium permanganate …show more content…
You may need to refer to a lecture textbook.
2) In the laboratory experiment, as the 4-methycyclohexene and water are being formed, they are constantly being distilled from the reaction mixture into a separate receiving flask. Explain how this process helps the reaction proceed with a higher yield.
3) What major alkene product is produced by dehydration of the following alcohols? You must draw the structure of the reactant alcohol and the final product in each answer.
a) cyclopentanol
b) 1-methylcyclohexanol
c) 2-methylcyclohexanol (Hint: look for a rearrangement and two products)
4) In this experiment, several mL of saturated sodium chloride is used to transfer crude product after the initial distillation. Why is saturated sodium chloride, rather than pure water, used for this procedure?
5) Write the structure of the two products that form when the Baeyer Test is performed on cyclobutene. S '08 M. Hauser (Survival Manual 7e) updated