To recrystallize the hydrazone from 2,4-dinitrophenyl hydrazine and salicylaldehyde, consider these solvents since ethanol is ineffective:

Please note that choose the solvent based on solubility tests for effective recrystallization

1. Water

2. Dilute Acetic Acid

3. Methanol

4. Acetonitrile

5. Dichloromethane/Hexane mix

Steps:

1. Test Solubility: Select a solvent that dissolves the hydrazone when hot but allows crystallization when cooled.

2. Dissolve and Cool: Heat to dissolve, then cool to precipitate.

3. Filter and Dry: Collect and dry the crystals.