Diethyl Ether → 5-Chloro-2,3-difluoropyridine

HRID 1762256Notes

Reaction equation

HRID 1762256 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.CCOCC>S1(CCCC1)(=O)=O.C1OCCOCCOCCOCCOCCOC1>[Cl:13][C:9]1[CH:10]=[C:11]([F:12])[C:6]([F:1])=[N:7][CH:8]=1

Participants

7

Reactant 4

HCID 3283Diethyl EtherHCID 25953Cesium fluorideHCID 522689Potassium FluorideHCID 109648772,5-Dichloro-3-fluoropyridine

Product 1

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

Reagents, catalysts & solvents 2

HCID 2855718-Crown-6CatalystHCID 31347SulfolaneSolvent3×

Conditions

Temperature
140 °C

Procedure

64.6 g (1.11 mol) of potassium fluoride and 11.25 g (0.074 mol) of caesium fluoride are suspended in 240 ml of sulfolane and the suspension is heated to 140° C. 50 mol of sulfolane are distilled off by decreasing the pressure and then 61.4 g (0.37 mol) of 2,5-dichloro-3-fluoropyridine and 1.45 g (0.0055 mol) of 18-crown-6 in 20 ml of sulfolane are added to the suspension. This reaction mixture is stirred for 35 hours at 140° C. and then taken up in ice water. The product is isolated from the aqueous mixture either by extraction with ether or by steam distillation, affording 48.7 g (88% of theory) of 5-chloro-2,3-difluoropyridine, b.p. 65°-66° C. at 133 mbar.

Sources & evidence

ORD record
ord-54befc6cb1d94b8a972b580f9904a1a2
Source dataset
uspto-grants-1989_05
Patent number
US04831148

Reaction notes

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