Concentrated sulfuric acid (4 mL) was slowly added to a stirred solution of 5-chloronicotinic acid (5 g, 31.8 mmol) in methanol (40 mL). The reaction mixture was placed in a 75°C oil bath and heated to reflux for 12 hours. After completion of the reaction, the mixture was cooled to room temperature and concentrated under reduced pressure to remove most of the methanol. The residue was diluted with distilled water (50 mL) and subsequently extracted with ethyl acetate (3 x 30 mL). The organic phases were combined and washed sequentially with saturated sodium bicarbonate solution (20 mL) and saturated sodium chloride solution (20 mL). The organic layer was dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure to afford methyl 5-chloronicotinate (4.4 g, 80% yield) as a white solid. The product was characterized by 1H NMR (400 MHz, CDCl3): δ 9.08 (d, J=1.6Hz, 1H), 8.73 (d, J=2.4Hz, 1H), 8.28-8.27 (t, J=2.0Hz, 1H), 3.96 (s, 3H). Mass spectrometry (MS) showed a molecular ion peak (M+1) of 172.12.
