Nitrogen protection in 1000ml three-necked flask was added chloroacetonitrile 50g (0.67mol), 200ml methanol sequentially and cooled to 0. Dissolve 1g of sodium methanol in 50ml of methanol and add it to the reaction vial dropwise. After dropwise addition, bring to room temperature and stir for 30 minutes. 1.06 ml of glacial acetic acid was added, and then 39 g (0.43 mol) of a 250 ml methanol solution of methyl hydrazinylformate was added dropwise to the resulting mixture. The dropwise addition was completed and stirring was continued for 30 minutes. Concentrate the reaction solution to nearly dry under reduced pressure, add 1000 ml of acetone, stirring and beating at room temperature for 30 min, filtered to obtain a light yellow solid, the solid was dried at 50 under blast to obtain 70.1 g of methyl 2-(2-chloro-1-ethylidene)hydrazinocarboxylate, yield: 93.1%, HPLC purity 99.8%.
