Hydrochloric Acid → (3-Aminophenyl)-2-pyridinylmethanone

The 2-(3-aminobenzoyl)pyridine may be prepared as follows: Stannous chloride in the dihydrate form (63 g) is added, at a temperature in the vicinity of 3° C., to a suspension of 2-(3-nitrobenzoyl)pyridine (19 g) in a 3.7N solution (360 cc) of hydrogen chloride in ethanol, in the course of 45 minutes. The suspension obtained is stirred at a temperature in the vicinity of 4° C. for 1 hour and 30 minutes, at a temperature in the vicinity of 20° C. for 1 hour and 30 minutes and then at a temperature in the vicinity of 80° C. for 1 hour and 30 minutes. The solvent is evaporated off under reduced pressure (20 mm Hg; 2.7 kPa) at a temperature in the vicinity of 50° C. The residue is taken up with distilled water (200 cc). The aqueous solution is adjusted to a pH in the region of 11 by adding an aqueous 10N sodium hydroxide solution at a temperature in the vicinity of 25° C., saturated with sodium chloride and then extracted 3 times with diethyl ether (600 cc in total). The ether extracts are combined, washed 3 times with a saturated aqueous sodium chloride solution (300 cc in total), dried over anhydrous magnesium sulphate, treated with decolourizing charcoal (0.5 g), filtered and concentrated to dryness under reduced pressure (20 mm Hg; 2.7 kPa) at a temperature in the vicinity of 40° C. A crude product (15.8 g) is obtained, which is chromatographed on an 8 cm diameter column containing silica (0.02-0.045 mm; 500 g). Elution is carried out with a mixture of cyclohexane and ethyl acetate (50:50 by volume) at a pressure of 0.4 bar (40 kPa), collecting 400 cc fractions. The first 7 fractions are discarded. The following 7 fractions are combined and concentrated to dryness under reduced pressure (20 mm Hg; 2.7 kPa) at a temperature in the vicinity of 50° C. 2-(3-Aminobenzoyl) pyridine (12 g) in the form of a red oil is thereby obtained and it is used in the subsequent syntheses.