Chapter%2019%20Cyclohexene%20from%20Cyclohexanol

1
Chapter 19 Cyclohexene from Cyclohexanol
2
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

3
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.

4
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

5
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.