Reaction #2146731

Reaction equation

phosphoric acid

1-isobutylcyclohexanol

phosphoric acid

1-isobutylcyclohexanol

→

1-isobutylcyclohex-1-ene

Solvents

Conditions

Workup

1. 1
   workup.DISTILLATIONWhile 1-isobutylcyclohex-1-ene and water distilled (boiling point 60° C.)
2. 2
   workup.ADDITIONAt the end of the addition
3. 3
   Temperatureheated further (vacuum from 170 to 40 mbar)
4. 4
   OtherThe distillate was decanted
5. 5
   Extractionthe water phase extracted with pentane (100 ml)
6. 6
   Dryingphases were dried (MgSO4)
7. 7
   Otherthe solvent evaporated

Procedure

In a flask equipped with a Vigreux-distillation apparatus, crude 1-isobutylcyclohexanol (200 g, 1.28 mol) was treated with phosphoric acid (100 g) and heated at 145° C. under vacuum (170 mbar). While 1-isobutylcyclohex-1-ene and water distilled (boiling point 60° C.), a second fraction of 1-isobutylcyclohexanol (492 g, 3.15 mol) was added dropwise in the reaction flask. At the end of the addition, the thick reaction mixture was diluted with paraffin oil (100 ml) and additional phosphoric acid (50 g) and heated further (vacuum from 170 to 40 mbar). The distillate was decanted and the water phase extracted with pentane (100 ml). The combined org. phases were dried (MgSO4) and the solvent evaporated to give 1-isobutylcyclohex-1-ene (448 g, 78%).

Source