2-carboxy-6-hydroxynaphthalene-5-sulfonic acid synthesis

Yield:137644-29-2 62%

Reaction Conditions:

with sulfuric acid at 20; for 4 h;

Steps:

4

Conc. sulfuric acid (95-98%, 12 ml) was cooled in ice-bath and 6-hydroxy-2-naphthanoic acid (2.83 g; 15.05 mmol) added in small portions. The reaction mixture was stirred at room temperature for 4 hours. The white solid was filtered and recrystallised from water. This gave yield of 62%. 'H NMR (DMSO-d6): [6] 7.09 (d, 1H, [JORTHO=8.] 7 Hz, aromatic), 7.90 (d, IH, [JORTHO=9.] 3 Hz, aromatic), 7.95 (d, IH, [JORTHO=8.] 7 Hz, aromatic), 8.41 (s, 1H, aromatic) and 8.66 (d, IH, Jortho=9.1 Hz, aromatic). Negative ion mass spectrum 267 m/z (100%).

References:

WO2003/104178,2003,A1 Location in patent:Page 67