Réaction #3011

Équation de réaction

hydrobromic acid

water

phenylmagnesium bromide

phenyl sulfoxide

→

triphenylsulfonium bromide

Solvants

benzene

ether

dichloromethane

benzene

Conditions de réaction

Traitement

1. 1
   AutreTo a 3-necked 1 L round bottom flask equipped with a still head
2. 2
   Autrethe diethyl ether removed under vacuo
3. 3
   Températureby gently heating
4. 4
   workup.ADDITIONAdditional benzene (150 ml) was added
5. 5
   Températurea gentle reflux under nitrogen
6. 6
   workup.ADDITIONOnce the addition
7. 7
   Températurethe reaction mixture was heated at
8. 8
   Températurea gentle reflux for 3 hours
9. 9
   TempératureThe reaction mixture was cooled (ice bath temperature)
10. 10
    AutreAfter separation of the layers
11. 11
    Extractionthe organic layer extracted
12. 12
    Extractionextracted with dichloromethane (200 ml)
13. 13
    Séchagedried (MgSO4 )
14. 14
    Concentrationconcentrated in vacuo
15. 15
    Autreto give the crude product as an off-white solid (14.50 g)
16. 16
    workup.ADDITIONadded
17. 17
    Autreto precipitate the salt
18. 18
    TempératureThe suspension was cooled in an ice bath for 1 hour
19. 19
    Autreto collecting the salt
20. 20
    Lavagewashing with ether

Mode opératoire

To a 3-necked 1 L round bottom flask equipped with a still head was added phenylmagnesium bromide (3 M in diethyl ether, 142 ml, 0.426 mol) followed by dry benzene (150 ml). The flask was connected to a water aspirator and the diethyl ether removed under vacuo by gently heating. Additional benzene (150 ml) was added and the solution brought to a gentle reflux under nitrogen. A solution of phenyl sulfoxide (17.23 g, 85.2 mmol) in benzene (100 ml) was added dropwise over 1.5 hours. Once the addition was complete, the reaction mixture was heated at a gentle reflux for 3 hours. The reaction mixture was cooled (ice bath temperature) while adding a solution of hydrobromic acid (25%, 200 ml). The resulting biphasic mixture was stirred at room temperature overnight. After separation of the layers, the organic layer extracted were combined and extracted with dichloromethane (200 ml), dried (MgSO4 ) and concentrated in vacuo to give the crude product as an off-white solid (14.50 g). The solid was taken up in the minimum mount of warm dichloromethane (100 ml) and four times the volume of ether added to precipitate the salt. The suspension was cooled in an ice bath for 1 hour prior to collecting the salt and washing with ether. In this way, triphenylsulfonium bromide was isolated as a white solid (14.40 g, 49%).

Source