Réaction #1398

Équation de réaction

4,4'-difluorodiphenylmethane

H2SO4

toluene

H2SO4

→

4,4'-difluorobenzophenone

Rendement 69.2%

Solvants

water

water

water

Conditions de réaction

Traitement

1. 1
   AutreTo a 250 mL round bottomed flask equipped with a heating mantle, overhead agitator
2. 2
   workup.ADDITIONthermometer, condenser, and addition funnel with a tube protruding below the liquid level
3. 3
   Lavageto wash the MnO2 beaker
4. 4
   workup.ADDITIONwere added to the flask
5. 5
   Autreto reach about 100° C. at which
6. 6
   workup.ADDITIONwere added to the addition funnel
7. 7
   Autreslowly rose to about 125° C.
8. 8
   workup.ADDITIONhad been added
9. 9
   TempératureThe mixture was heated
10. 10
    Autreafter approximately 12 hours
11. 11
    Températureto cool to 100° C.
12. 12
    Autrefitted with No
13. 13
    Filtration42 filter paper
14. 14
    Autreto form a filter pre-coat
15. 15
    Filtrationvacuum filtered
16. 16
    Lavageto wash the flask
17. 17
    LavageThe filter cake was then washed with 100 g toluene
18. 18
    Températureheated to about 50° to 70° C.
19. 19
    Autrethe filtrate phase separated
20. 20
    AutreThe toluene was removed from the organic phase
21. 21
    Températureby heating to approximately 65° C. at 10 mm Hg
22. 22
    AutreThe solids were recrystallized from a hexane solvent

Mode opératoire

To a 250 mL round bottomed flask equipped with a heating mantle, overhead agitator, thermometer, condenser, and addition funnel with a tube protruding below the liquid level was added 10.6 g 4,4'-difluorodiphenylmethane (0.051 moles). Agitation was begun and a slurry of 20.5 g MnO2 (0.195 moles) in 30 g water was added to the flask. About 30 g of water were used to wash the MnO2 beaker and were added to the flask. The mixture was allowed to reach about 100° C. at which point 50 g H2SO4 (0.487 moles) were added to the addition funnel. The H2SO4 was then added dropwise into the flask and the reaction temperature slowly rose to about 125° C. when all of the acid had been added. The mixture was heated to maintain the temperature at about 125° C. until gas chromatography showed complete conversion after approximately 12 hours. The reaction mixture was allowed to cool to 100° C. and 50 g toluene were added to the mixture. A slurry of 6 g diatomaceous earth in 30 g water was poured into a vacuum Buchner funnel fitted with No. 42 filter paper to form a filter pre-coat. The contents of the round bottomed flask were then vacuum filtered. 10 g toluene was used to wash the flask and, subsequently, the filter cake. The filter cake was then washed with 100 g toluene heated to about 50° to 70° C. and the filtrate phase separated. The toluene was removed from the organic phase by heating to approximately 65° C. at 10 mm Hg. The 10 g yellow solids assayed as 95% pure 4,4'-difluorobenzophenone for an 84% yield. The solids were recrystallized from a hexane solvent leaving 7.7 g crystalline 4,4'-difluorobenzophenone for a 68% yield.

Source