59702-31-7

110-72-5

95-92-1

59702-31-7

A. Prepare Mixed Solution A by dissolving 11 g of N-ethyl ethylenediamine in 8 g of anhydrous methanol.B. Add 25 ml of anhydrous methanol to a dry three-necked flask and 2 g of glacial acetic acid under stirring, and when it is completely dissolved, 11 g of diethyl oxalate was slowly added at 25-30 °C, and the temperature of the reaction system was subsequently lowered to 15-20 °C. This mixed solution was transferred to a dropping funnel and set aside.C. Mixed Solution A was slowly added dropwise to Mixed Solution B, keeping the reaction temperature between 30-50 °C for 30-50 min. After the reaction was completed, the temperature was raised to 50°C and the reaction was continued for 1 hour. At the end of the reaction, methanol was removed by concentration under reduced pressure.D. 66 ml of solvent B was added to the reaction mixture and the temperature of the system was slowly lowered from 50 °C to room temperature (25-30 °C) to allow the product to crystallize slowly. Finally 14.77 g of N-ethyl-2,3-dioxopiperazine was obtained in 83.21% yield and 99.32% purity.