Reaction #54846

Reaction equation

sodamide

ammonia

3-Chloro-4-cyclohexylacetophenone

phosphorus pentachloride

→

3-chloro-4-cyclohexylethynylbenzene

Solvents

THF

ether

water

Conditions

Workup

1. 1
   Otherequipped with a mechanical stirrer, a condenser
2. 2
   Otherconnected to a nitrogen inlet
3. 3
   OtherThe cooled reaction mixture
4. 4
   workup.ADDITIONis poured onto 800 g
5. 5
   Extractionof ice and extracted with 3× 500 ml
6. 6
   WashThe ether fraction is washed with 2× 100 ml water 4× 100 ml of 5% sodium hydroxide, 3× 50 ml water, 2× 50 ml of saturated saline
7. 7
   Dryingdried over sodium sulfate
8. 8
   OtherThe ether is removed
9. 9
   Otherto give the chlorinated intermediate
10. 10
    workup.STIRRINGto stir at room temperature overnight
11. 11
    WashThe ether fraction is washed with 3× 50 ml water and 50 ml of saturated saline
12. 12
    Dryingis dried over sodium sulfate
13. 13
    OtherRemoval of solvent
14. 14
    Othergives a residue which
15. 15
    workup.DISTILLATIONis distilled

Procedure

3-Chloro-4-cyclohexylacetophenone (0.25 moles) and phosphorus pentachloride (0.31 moles) are placed in a 3-necked flask equipped with a mechanical stirrer, a condenser connected to a nitrogen inlet, and a thermometer. The mixture is stirred at 33°-35° C. for 3 days. The cooled reaction mixture is poured onto 800 g. of ice and extracted with 3× 500 ml. of ether. The ether fraction is washed with 2× 100 ml water 4× 100 ml of 5% sodium hydroxide, 3× 50 ml water, 2× 50 ml of saturated saline and dried over sodium sulfate. The ether is removed to give the chlorinated intermediate. The intermediate is dissolved in anhydrous THF (200 ml) and is added dropwise to a freshly prepared solution of sodamide in liquid ammonia, using a dry-ice condenser. The reaction mixture is allowed to stir at room temperature overnight; then, it is poured into 50 ml of water and 500 ml of ether. The ether fraction is washed with 3× 50 ml water and 50 ml of saturated saline and is dried over sodium sulfate. Removal of solvent gives a residue which is distilled to give 3-chloro-4-cyclohexylethynylbenzene.

Source