Sodium Iodide → 6-Iodopyridine-3-carboxylic acid

Participants

Reaction Steps

Sodium iodide (20.59 g, 137.40 mmol) was cooled to -78° C. under argon and then hydriodic acid (97.13 g, 759.34 mmol) was added. The cooling bath was removed and the suspension was stirred for 5 minutes. To this mixture was added 6-chloronicotinic acid (22.09 g, 140.20 mmol) and the resulting mixture was slowly warmed to ambient temperature with stirring. The mixture was heated to reflux at 125° C. for 24 hours, cooled to ambient temperature and poured into acetone (500 ml) at 0° C. The yellow solid was collected by filtration and washed with 200 ml of 1N aqueous NaHSO3 solution. Recrystallization from methanol (crystals were washed with ethyl ether) afforded the title compound as white crystals: mp 177-179° C. [lit. mp 187-192, Newkome et al. "Reductive Dehalogenation of Electron-Poor Heterocycles: Nicotinic Acid Derivatives" J. Org. Chem. 51: 953-954 (1986). 1H NMR (DMSO-d6): δ 8.81 (1H, dd, J=0.8, 2.4 Hz), 8.01 (1H, dd, J=0.8, 8.2 Hz), 7.91 (1H, dd, J=2.4, 8.2 Hz).

Provenance & Evidence