Methyl 4,6-dichloronicotinate could be used to synthesize 4,6-dichloronicotinic acid. Specifically, to a solution of methyl 4,6-dichloronicotinate in a mixture of THF (400 mL), MeOH (100 mL), and H2O (100 mL), a solution of NaOH (10 g) in 40 mL H2O was added. The mixture was stirred for 40 min at room temperature. Then, the solvents were reduced and acidified with concentrated HCl to a pH of about 2. It was extracted using a mixture of Et2O/EtOAc, and the organic layer was dried with Na2SO4. The solvents were removed, and the residue was dried in vacuo to obtain 4,6-dichloronicotinic acid as a white solid (12.3 g, 69% yield).
