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A white powder with a slight Chlorine smell. Dichlorodimethylhydantoin is a chlorinating agent that is used in powder type household bleaches (Sage's Dry Bleach, Colgate's Pruf). When kept dry, it has a long shelf life with only minor loss of chlorine. On contact with water, it forms Hypochlorous acid that acts as a Bleaching agent and Disinfectant.

Synonyms and Related Terms

1,3-dichloro-5,5-dimethylhydantoin; dichloratin; 2,4-Imidazolidineione; DDH; Dactin; Halane; household laundry bleach

Chemical structure



  • Irritating to eyes, nose, skin and lungs. Combustible with the evolution of chlorine.
  • Fisher Scientific: MSDS

Physical and Chemical Properties

  • Soluble in chlorinated solvents, alcohols and benzene.
  • Slightly soluble in water forming a solution with pH about 4.4
Composition C5H6Cl2N2O2
CAS 118-52-5
Melting Point 132 C
Density 1.5 g/ml
Molecular Weight mol. wt. = 197.02

Resources and Citations

  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 3115