[¦par·ə ‚dī¦meth·əl¦am·ə‚nō‚ben·zəl′rō·də‚nēn] (organic chemistry) C12H12N2OS2 Deep red, needlelike crystals that decompose at 270°C; soluble in strong acids; used in acetone solution for the detection of ions such as silver, mercury, copper, gold, palladium, and platinum.