Chapter 19 Cyclohexene from Cyclohexanol

Purpose In this experiment cyclohexanol undergoes acid-catalized dehydration to give cyclohexene. The product is distilled from the reaction mixture along with the water generated. Toluene is used as a chaser solvent. The distillate is washed with salt solution, dried, and fractionally distilled

Reaction Mechanism The mechanism involves initial rapid protonation of the hydroxyl group by the phosphoric acid, followed by loss of water to give the unstable secondary carbocation. Quick loss of the proton from this carbocationic intermediate leads to the target alkene.

(Moles Product / Moles Starting Material) x 100 = % Yield Comments Follow macroscale procedure (Ch 19.2) Follow the lab handout for all experimental procedures. Wearing rubber gloves is necessary during this lab. You will work with toxic and corrosive compounds. Calculate yield. Low to moderate yields should are typical. (Moles Product / Moles Starting Material) x 100 = % Yield

Safety Flammable solvents are used in this experiment, keep away from any open flame. Concentrated phosporic acid is very corrosive, wear gloves and handle with care. Cyclohexanol is harmful by inhalation and if swallowed, and irritating to respiratory system and skin. Do not swallow and inhale, avoid contact with skin and eyes. Cyclohexene is highly flammable, and harmful in contact with skin and if swallowed. May cause serious lung damage if swallowed. Do not swallow and inhale, avoid contact with skin and eyes.