Synthesis
General procedure for the synthesis of 2-furancarbohydrazide from furan-2-carboxamide and 4-methyl-3-penten-2-one hydrazone: 111.1 g of furan-2-carboxamide was placed in a four-necked flask fitted with a stirrer, a dropping funnel, a thermometer, and a distillation column, and 224 g of acetone acridine was added. Stirring was turned on and the reaction mixture was heated to 100 to 120 °C to ensure complete dissolution of furan-2-carboxamide in acetone acridazine. Subsequently, 70 ml of water was slowly added through a dropping funnel to maintain the reaction temperature between 100 °C and 120 °C. The ammonia produced during the reaction was exported through a distillation column and the ammonia was recovered by condensation at 54°C to 58°C. The condensed water vapor was returned to the reaction flask to continue participating in the reaction. After the water droplet addition was completed, heating of the reaction mixture was continued. The progress of the reaction was monitored by analyzing the amount of furan-2-carboxamide in the reaction solution. Once the furan-2-carboxamide was fully reacted, the flask was distilled with acetone and water fully connected under nitrogen protection. The residual solid in the flask was recrystallized with ethanol and dried to give 119.6 g of 2-furancarboxamide.
