Single-step synthesis of 2-methylquinoxaline from 1,2-phenylenediamine and 1,2-propanediol over modified HY zeolites

Abstract

The cyclization reaction of 1,2-phenylenediamine and 1,2-propanediol for the synthesis of 2-methylquinoxaline (2-MQ) was carried out over the HY, LaHY, PbHY, CuHY and CrHY zeolites at 350 °C. The catalytic activity towards the yield of 2-MQ followed the order: PbHY > MnHY > CrHY > LaHY > HY > CuHY. The medium acidic catalysts like Pb- and Cr-modified HY zeolites gave high activity. The high acidity of the catalyst and high reaction temperatures decrease the yield and selectivity of the product. The maximum yield of 82.1% of 2-MQ with 99.2% conversion of 1,2-phenylenediamine was obtained over a PbHY catalyst at 350 °C.