2-Ethyl-3-methylpyrazine

600-14-6

107-15-3

15707-23-0

2,3-Pentanedione, ethylenediamine and anhydrous ethanol were mixed in a three-necked flask at -5 to 3°C in a mass ratio of 1:1.1:70 and the reaction was stirred for 7 hours. After completion of the reaction, the system was slowly warmed to room temperature and stirring was continued for 3 hours. Subsequently, the temperature was raised to 65-70°C and refluxed for 4 hours. After the reaction mixture was cooled to 30-40 °C, xylene and potassium hydroxide catalyst was added to a three-necked flask, where the mass ratio of 2,3-pentanedione, potassium hydroxide to xylene was 1:0.8:2.8. Heating was continued to 65-70 °C and refluxed for 5 h. The reaction mixture was then cooled to room temperature and stirred for 7 h. The reaction mixture was then cooled to room temperature and stirred for 4 h. After the reaction was completed, it was cooled to room temperature and subjected to filtration. The filtrate was distilled at atmospheric pressure and the resulting concentrate was extracted with saturated brine solution, the organic phases were combined and dried with anhydrous sodium sulfate. The dried organic phase was filtered and subjected to atmospheric pressure distillation to collect the 55-60 °C/1.33 kPa fraction to give 2-ethyl-3-methylpyrazine in more than 93.5% product yield.