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Alkenes from Alcohols: Cyclohexene from Cyclohexanol

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I. Objectives * Be able to prepare cyclohexene from the dehydration of cyclohexanol * Understand the mechanisms of the dehydration reaction (acid-catalyzed dehydration). * Know how to use the necessary equipment for this reaction, such as the fractioning column. * Obtain positive results in unsaturation tests for the presence of carbon-carbon double bond (cyclohexene).

II. Background
Cyclohexanol, the reagent of this experiment, is used in the production of nylon, paints, plastics, detergents, textiles and pesticides. The dehydration of cyclohexanol to cyclohexene can be accomplished by pyrolysis of the cyclic secondary alcohol with an acid catalyst at a moderate temperature or by distillation over …show more content…

X. Results * After distillation the product was divided into two test tubes: One adding Br2 and the other one KMnO4 * Both test resulted in a colorless liquid, meaning a positive result for carbon-carbon double bond presence (cyclohexene).
Test 1: Addition of Br2:

Test 2: Addition of KMnO4:

* Both tests resulted in a colorless liquid, giving positive results for carbon-carbon double bond presence (cyclohexene).

XI. Discussion/ Conclusion
An alcohol can be dehydrated to form an alkene in the presence of a strong acid. We used 85% phosphoric acid and the alcohol is cyclohexanol. The reaction is carried out in a fractional distillation apparatus. As the alcohol and acid are heated, alkene and water are produced and distilled into a collection vial. The distillation process was long and we needed to be careful to not get any other product that cyclohexene; that is, we had to observe temperature changes, so the temperature would not affect the product yield. The distillation was continued until the temperature rose well over the boiling point of cyclohexene. At this point we assumed that the product has distilled into the collection vial.
To test our product for the presence of cyclohexene in the product, we

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