1. 1700 g of ethyl pyruvate is slowly added dropwise to 1400 g of a 35% hydrogen peroxide solution at -20°C to -10°C (preferably -10°C).
2. after holding the reaction for 30 minutes, 1400 g of 4-bromopyridine hydrochloride (compound 1) was added to ice water.
3. The pH of the reaction mixture was adjusted to 8-9 using potassium carbonate at a temperature below 10 °C.
4. The reaction mixture was extracted twice with 7 L of dichloromethane (DCM), the organic phases were combined and dried.
5. The dried organic phase was transferred to a 50L reaction flask and 1.4L of water, 4073g of ferrous sulfate heptahydrate and 448mL of concentrated sulfuric acid were added and stirred at room temperature.
6. Under the condition of -10°C to 0°C (preferably -5°C), the pre-prepared ethyl pyruvate/hydrogen peroxide solution was added and the reaction was continued for 4 hours.
7. After completion of the reaction, the reaction mixture was extracted with 7 L of water and the solvent was removed by rotary evaporation to afford 1390 g of ethyl 4-bromopyridine-2-carboxylate (compound 2) in 82% yield.
