2,4-Dinitrophenylhydrazone (DNP) Test. Glassware must be absolutely free of acetone (WHY?) Dissolve approximately 0.2 g of unknown in 1 mL of ethanol, add 3 mL of the DNP reagent, cap, and shake the test tube. If a precipitate is not obtained immediately, warm the solution gently in a warm water bath and let it stand for 10-15 minutes. Positive test: precipitate. Control positive test: acetone. NO NHNH NO2 N N ON ON 'R R 2,4-dinitrophenylhydrazine hydrazone product beautifully colored precipitate What functional group(s) would you expect to react with a hydrazine (a fancy 10 amine) to give an insoluble hydrazone product? Why would two similar functional groups react at different rates