Cesium fluoride → 2,3-Difluoro-5-(trifluoromethyl)pyridine

HRID 1762258Notes

Reaction equation

[F-:1].[K+].[F-].[Cs+].Cl[C:6]1[C:11]([F:12])=[CH:10][C:9]([C:13]([F:16])([F:15])[F:14])=[CH:8][N:7]=1>S1(CCCC1)(=O)=O.C1OCCOCCOCCOCCOCCOC1>[F:1][C:6]1[C:11]([F:12])=[CH:10][C:9]([C:13]([F:16])([F:15])[F:14])=[CH:8][N:7]=1

Participants

Conditions

Temperature: 140 °C

Procedure

47.7 g (0.82 mol) of potassium fluoride and 10.0 g (0.065 mol) of caesium fluoride are suspended in 300 ml of sulfolane and the suspension is heated to 140° C. 60 ml of sulfolane are distilled off by decreasing the pressure and subsequently 65.6 g (0.329 mol) of 2-chloro-3-fluoro-5-trifluoromethylpyridine and 1.3 g (0.004 mol) of 18-crown-6 are added. The reaction mixture is stirred for 48 hours at 140° C. and subsequently distilled by introducing steam. The oil is separated and the aqueous phase is extracted twice with a small amount of ether. The organic phases are purified, dried with a small amount of magnesium sulfate and filtered. Distillation affords 54.8 g (91% of theory) of 2,3-difluoro-5-trifluoromethylpyridine, b.p. 100°-102° C. (980 mbar).

Workup

distillation60 ml of sulfolane are distilled off
additionare added
distillationsubsequently distilled
additionby introducing steam
customThe oil is separated
extractionthe aqueous phase is extracted twice with a small amount of ether
customThe organic phases are purified
dry with materialdried with a small amount of magnesium sulfate
filtrationfiltered
distillationDistillation

Sources & evidence

ORD record: ord-923ff52ecd2149ccb3892b9580af52fe
Source dataset: uspto-grants-1989_05
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US04831148

Reaction notes

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