General procedure: 2,6-dichloronicotinic acid (25.5 g, 0.1328 mol) was mixed with ethanol (200 mL) under nitrogen protection and 96% sulfuric acid (1.7 g) was added as catalyst. The reaction mixture was heated to reflux temperature for esterification. Upon completion of the reaction, ethyl 2,6-dichloronicotinate was obtained as a gray solid (24.89 g, 0.1131 mol, 85.2% yield) after conventional post-treatment. The product was characterized by 1H NMR (300 MHz, DMSO-d6): δ 8.30 (d, J = 8.1 Hz, 1H), 7.71 (d, J = 8.1 Hz, 1H), 4.33 (q, J = 7.2 Hz, 2H) and 1.30 (t, J = 7.2 Hz, 3H) ppm.
