Ethyl 4-bromo-1H-pyrrole-2-carboxylate

72652-32-5

141-52-6

433267-55-1

Anhydrous ethanol (950.0 kg) was added to a 3000 L glass-lined reactor followed by 1-(4-bromo-1H-pyrrol-2-yl)-2,2,2-trichloroacetophenone (342.7 kg), keeping the reaction temperature at 20-30 °C. The reaction mixture was cooled to 0-5°C over about 2 hours. At this temperature, 21% sodium ethanol solution (36.4 kg) was slowly added dropwise over 1-1.5 hours. Upon completion of the dropwise addition, the reaction mixture was warmed to 25-30 °C and monitored to ensure that the content of 1-(4-bromo-1H-pyrrol-2-yl)-2,2,2-trichloroacetophenone was reduced to <1.0%. Subsequently, the reaction mixture was concentrated at a temperature not exceeding 50 °C until the remaining volume was 1.3-1.4 times the original volume. The concentrate was cooled to 25-30 °C and quenched by slowly pouring it into cold water (3427.0 kg) over about 2 hours. After quenching, the mixture was stirred at 0-5°C for about 2 hours to promote crystallization. After crystallization was completed, the solid product was separated by filtration and the filter cake was washed with cold water. Finally, the resulting solid was dried at 30-40 °C for 40-45 h to afford ethyl 4-bromo-1H-pyrrole-2-carboxylate (234.3 kg) with 99.9% purity and 91.3% yield.