Sodium Hydroxide → 1,4-Diethoxynaphthalene-2,3-dicarboxylic acid

To a stirred solution of diethyl 1,4-bis(ethyloxy)-2,3-naphthalenedicarboxylate (1343 g, 3.73 mol) in ethanol (5.5 L) was added 2M sodium hydroxide solution (5.5 L, 11.0 mol). The reaction mixture was heated to reflux for 8 hours, with the reaction progress monitored by 1H-nmr spectroscopy. The mixture was then cooled to 0° C. for 18 hours before isolation of the crystallised solid by filtration, washing with ethanol (5 L) and drying in a vacuum oven at 60° C. to constant mass gave the desired product as a white solid (903.7 g, ˜11% water remains by Karl-Fischer, 62% yield).