production method | a mixture of 85% hydrazine hydrate and 95% ethanol was cooled to 10 °c, the ethyl chloroformate and the sodium carbonate solution were added dropwise with stirring, and the feeding rate was controlled to keep the ethyl chloroformate in excess, and the addition was completed before the sodium carbonate solution, and the feeding temperature was maintained at 20 ° C. Or higher. After addition, the reaction was continued with stirring for 0.5h, the precipitate was filtered off, washed thoroughly with water and then dried under vacuum at 80 ° C. To obtain a finished product with a yield of 81-85%. |