Synthesis
The general procedure for the synthesis of 4-formamidopyridine hydrochloride from 4-cyanopyridine was as follows: 4-cyanopyridine (20.0 g, 0.2 mol) was dissolved in anhydrous methanol (200 mL), followed by a one-time addition of powdered sodium methanol (1.1 g, 20 mmol). The reaction mixture was stirred at room temperature overnight. Next, ammonium chloride (16.5 g, 0.31 mol) was added and the reaction mixture was heated to reflux for 4 hours, after which it was cooled to room temperature. After the solvent was removed by evaporation, anhydrous ethanol (300 mL) was added. The mixture was heated to reflux and maintained for 15 min before the solid was removed by filtration. The filtrate was cooled to room temperature and allowed to stand overnight. The filtrate was filtered again to remove inorganic salts and the reaction mixture was subsequently concentrated to about one-third of the original volume to give 24.0 g (76% yield) of 4-formamidinopyridine hydrochloride by final filtration.
References
[1] Bioorganic and Medicinal Chemistry Letters, 2016, vol. 26, # 15, p. 3487 - 3490
[2] Bioorganic and Medicinal Chemistry, 2011, vol. 19, # 11, p. 3347 - 3356
[3] Bioorganic and Medicinal Chemistry Letters, 2005, vol. 15, # 12, p. 2990 - 2993
[4] Journal of Medicinal Chemistry, 1990, vol. 33, # 4, p. 1230 - 1241
[5] Patent: US5294612, 1994, A
