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A white crystalline compound. Hydroquinone is used in black and white photographic processing as a reducing agent. It is also used as an antioxidant in polymers and as a stabilizer in paints and varnishes.

Synonyms and Related Terms

1,4-benzenediol; p-dihydroxybenzene; hydroquinol; quinol; Aida; Black and White Bleaching Cream; Eldoquin; Eldopaque; Tecquinol; Quinol; hydrochinon; hydrokinone; 1,4-dihydroxybenzene;



Chemical structure


Other Properties

Soluble in water, ethanol and ether. Slightly soluble in benzene.

Composition C6H4(OH)2
CAS 123-31-9
Melting Point 170-171
Density 1.332
Molecular Weight mol. wt.=110.11
Boiling Point 285-287

Hazards and Safety

Combustible. Flash point =165 C (329 F).

Highly toxic by ingestion and inhalation. Skin contact can cause severe irritation.

Mallinckrodt Baker: MSDS

Sources Checked for Data in Record

  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
  • The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 4796
  • Website address 1 Comment: www.jetcity.com/~mrjones/chemdesc.htm - photographic chemicals
  • The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998