Cesium fluoride → 5-Chloro-2,3-difluoropyridine

HRID 359644Notes

Reaction equation

HRID 359644 reaction equation
[F-:1].[K+].[F-].[Cs+].Cl[C:6]1[C:11]([F:12])=[CH:10][C:9]([Cl:13])=[CH:8][N:7]=1>S1(CCCC1)(=O)=O>[Cl:13][C:9]1[CH:10]=[C:11]([F:12])[C:6]([F:1])=[N:7][CH:8]=1

Participants

5

Reactant 3

HCID 25953Cesium fluorideHCID 522689Potassium FluorideHCID 109648772,5-Dichloro-3-fluoropyridine

Product 1

HCID 27832485-Chloro-2,3-difluoropyridineYield 88%

Reagents, catalysts & solvents 1

HCID 31347SulfolaneSolvent3×

Conditions

Temperature
140 °C

Procedure

A suspension of 64.6 g (1.1 mol) of potassium fluoride and 11.25 g (0.075 mol) of cesium-fluoride in 240 ml of sulfolane (1,1-dioxo-tetrahydrothiophene) is heated to 140° C. By reducing the pressure 50 ml of sulfolane are distilled off. To the suspension a solution of 61.4 g (0.37 mol) of 2,5-dichloro-3-fluoropyridine in 20 ml of sulfolane is added. The reaction-mixture is then stirred for 35 hours at a temperature of 140°, cooled and poured into ice/water. The organic material is extracted with ether. The ethereal layer is washed with water dried over magnesium sulfate, filtered and evaporated to yield 48.7 g of a colourless oil (88% of the theory) which boils at 65°-66° at 133 mbar.

Workup

  1. distillationare distilled off
  2. temperaturecooled
  3. extractionThe organic material is extracted with ether
  4. washThe ethereal layer is washed with water
  5. dry with materialdried over magnesium sulfate
  6. filtrationfiltered
  7. customevaporated

Sources & evidence

ORD record
ord-b6ef0c63f4bc49209b476a983bb8bca8
Source dataset
uspto-grants-1991_03
Patent number
US05002604

Reaction notes

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