Malic Acid → HCID 178507297, compound

Participants

Reaction Conditions

Reaction Steps

2,6-Diaminopyridine (167 g, 1.53 mol) was added in portions to sulfuric acid (1.14 kg, 11.7 mol) at 40° C. The temperature of the solution was maintained at 40-50° C. during the addition with a water bath. When all of the 2,6-diaminopyridine was dissolved, the solution was cooled to 20° C. Malic acid (206 g, 1.53 mol) was added to the solution and the reaction mixture was gradually heated to 110° C. over 90 minutes. The mixture was stirred at 110-120° C. for one hour, cooled to room temperature, and poured slowly into a cold brine solution (167 g NaCl, 1.6 kg ice water). The quenched mixture was stirred at room temperature for one hour and filtered. The material was washed with hexanes (335 mL) and dried at 60° C. under vacuum to yield 2-amino-7-hydroxy-1,8-naphthyridine sulfuric acid salt as a yellow solid: 354 g, 89% yield; MS (DCl) M+1 at 162, 100%; 1H NMR (200 MHz, DMSO-d6) δ 4.32 (br. s, 5H, —OH, —NH2, H2SO4), 6.41 (d, J=9.0 Hz, 1H, C6), 6.56 (d J=9.0 Hz, 1H, C5), 7.85 (d J=6.6 Hz, 1H, C3), 7.91 (d J=6.6 Hz, 1H, C4).

Provenance & Evidence