This pyrazolone analog, also known as 2,4-dihydro-2,5-dimethyl-3h-pyrazol-3-one, presents as a very pale yellow to pale reddish yellow crystalline powder. Store in a cool and dark place. 1,3-Dimethyl-5-pyrazolone is known to be incompatible with oxidizing agents and should not be stored or handled in their vicinity.