2,2'-Bipyridine → 2-Pyridinecarboxylic acid, 4,5,6-trichloro-

An 8 mL scintillation vial was charged with NiCl2.6H2O (87.8 mg, 0.369 mmol) and 2,2′-bipyridine (119.2 mg, 0.763 mmol). The vial was closed and purged with nitrogen for 10 min, after which the vial was charged with DMF (4.5 mL) and water (0.5 mL). The mixture was allowed to stir for 5 min until a clear, bright blue solution was present. To the vial was added zinc dust (1.657 g, 25.3 mmol), and the mixture was allowed to stir under nitrogen for 35 min until a very dark blue/black solution was present. Solid 3,4,5,6-tetrachloropicolinic acid (0.831 g, 3.2 mmol) was added through the top of the reactor. The reaction mixture was allowed to stir at 27° C. for 5.5 h. The crude reaction mixture was filtered through a medium frit filter, and the filter cake was washed with DMF (2×). The resulting filtrate was diluted with an equal volume of 10% HCl (aq) to yield a clear, light yellow solution which was allowed to stir overnight at ambient temperature. The white solid was collected by vacuum filtration and was dried in an inert heating oven (50° C.; 1 h) to give the title compound (0.60 g, 83.1%) that was 69% pure as analyzed by calibrated HPLC.