Combine 13.34 g of 3-nitrophthalhydrazide and 75 mL of 4.5M ammonia with stirring, then add 13.94 g of thiourea dioxide, stir very vigorously, the solution may start to boil. Heat the mixture to 90°C for 30 minutes. Neutralize the solution to about pH 6.5 with glacial acetic acid. Cool in a fridge overnight, filter and recrystallize in hot ethanol.
3-Nitrophthalhydrazide and the ammonia solution
The compounds were combined and the thiourea dioxide was added
The mixture was refluxed for 30 minutes
The solution was cooled down and the glacial acetic acid was added to neutralize it
After the neutralization, the luminol precipitated in a fridge in 24 h