Tetrachloropicolinonitrile → 3-Chloro-4,5,6-trifluoro-2-pyridinecarbonitrile

Participants

Reaction Conditions

Reaction Steps

A mixture of 3,4,5,6-tetrachloropicolinonitrile (16.1 g, 66 millimoles (mmol)) and 3,4,5,6-tetrafluoropicolinonitrile (5.9 g, 33 mmol) were heated to 160° C. under nitrogen to form a solution. To this stirred solution was added tetrabutyl phosphonium chloride (Bu4PCl; 0.36 g, 1.2 mmol), and the solution was held at 160° C. for 1 h. An aliquot was dissolved in methylene chloride (CH2Cl2) and passed through a short pad of silica gel before GC analysis. The profile of halogenated picolinonitriles was: 11.2% Cl4-PN; 11.3% 4,6-F2—PN; 2.3% 5,6-F2—PN; 19% 3,6-F2—PN; 52.6% 6-F-PN and 3.6% 4-F-PN. About 80% of the mixture is useful in the halogen exchange reaction to produce 3-chloro-4,5,6-trifluoropicolinonitrile.

Provenance & Evidence