Combine 35 g of hydrazine sulfate and 135 mL of water and with stirring add 85 g of sodium acetate, boil for 5 minutes and cool down to 70°C. Add 75 mL of ethanol filter and wash with 75 mL of hot ethanol. To a reflux apparatus add 50.5 g of 2,4-dinitrochlorobenzene, 250 mL of ethanol and the filtrate, reflux for 1h with stirring. Cool down, filter and wash with 50 mL of ethanol and 50 mL of water. Distill half of the ethanol off from the filtrate and collect the product. Recrystallize in n-butyl alcohol.
Refluxing the mixture
The pure 2,4-dinitrophenylhydrazine