Example 3: Preparation of 2-methyl-5-pyridylacetic acid; 2-(6-methylpyridin-3-yl)morpholinoethylthione (25 g) was dissolved in 200 mL of ethanol, followed by addition of a 60% aqueous NaOH solution (21 g NaOH dissolved in 25 mL of water). The reaction mixture was heated to 80 °C and refluxed for 17 hours. After completion of the reaction, it was cooled to room temperature and the solvent was removed by rotary evaporation. A small amount of water was added to dissolve the residue and the pH was adjusted with concentrated hydrochloric acid to 2. The insoluble material was removed by filtration and the filtrate was extracted twice with ether, the ether layers were combined and washed once with distilled water. The aqueous layer was retained and set aside. The water in the solvent was removed by rotary evaporation and the product was dried in a vacuum drying oven for 24 h to give 2-methyl-5-pyridylacetic acid (11 g) in about 70% yield. The product was characterized by 1H-NMR (400 MHz, DMSO-d6): δ 2.43 (3H, s, CH3); 3.57 (2H, s, CH2); 7.17-7.19 (1H, d, ArH); 7.53-7.56 (1H, dd, ArH); 8.30-8.31 (1H, d, ArH); 12.42 (1H, s , COOH).
