[¦wən ‚klȯr·ō ¦tü ¦fȯr dī‚nī·trō′ben‚zēn] (organic chemistry) C6H3ClN2O4 Yellow crystals with a melting point of 52-54°C; soluble in hot alcohol, ether, and benzene; used as a reagent in the determination of pyridine compounds such as nicotinic acid, and nicotinamide.