The end of the reaction of ethanal with Brady's reagent (dinitrophenylhydrazine, 2, 4-DNPH). Brady's reagent is a yellow solution that is used as qualitative test for carbonyl groups associated with aldehydes and ketones and tests for a carbon-oxygen double bond. Ethanal or acetaldehyde (CH3CHO) is an? organic chemical compound, an important aldehyde. When ethanal is added to Brady's reagent, an orange precipitate is formed (known as ethanal 2, 4-dinitrophenylhydrazone.)