501-53-1

5331-43-1

1. General procedure for the synthesis of benzyl hydrazinecarboxylate: In a three-necked reaction flask equipped with temperature control, hydrazine hydrate (2.0 mol), potassium carbonate (2.0 mol), and 50 mL of tetrahydrofuran are added sequentially. After cooling the reaction system to -20°C, benzyl chloroformate (2.0 mol) was slowly added. After completion of the reaction, stirring was continued for 2 h. The potassium carbonate was subsequently removed by filtration and washed with water. The organic phase was concentrated to give the crude product of benzyl hydrazinecarboxylate (95.0% yield, 96.0% purity as determined by high performance gas chromatography (GC)). 2. Purification of the crude product of benzyl hydrazinecarboxylate: In another three-necked reaction flask, add the crude product of benzyl hydrazinecarboxylate (40.0 g, purity 96.0%, determined by high performance gas chromatography (GC)) and 400 mL of dichloromethane. 80 mL of 30% hydrochloric acid was added dropwise to the reaction system and solid precipitation was observed. 150 mL of water was added to dissolve some of the solids. The organic layer was separated and retained. Add 80 mL of ammonia dropwise to the aqueous layer and adjust the pH to alkaline. The aqueous layer was extracted three times with 250 mL of dichloromethane. The organic phases were combined and concentrated to give purified benzyl hydrazinecarboxylate (36.0 g, 99.5% purity, 90.0% yield as determined by high performance gas chromatography (GC)).