C6H4(OH)2

from The Collaborative International Dictionary of English v.0.48

Hydroquinone \Hy`dro*qui"none\, n. [Hydro-, 2 + quinone.]
   (Chem.)
   A white crystalline substance, {C6H4(OH)2}, obtained by the
   reduction of quinone. It is a diacid phenol, resembling, and
   metameric with, pyrocatechin and resorcin. Called also
   {dihydroxy benzene}.
   [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

Oxyphenol \Ox`y*phe"nol\, n. (Chem.)
   A phenol, {C6H4(OH)2}, produced by the distillation of
   catechin; called also {oxyphenic acid}, and now
   {pyrocatechin}.
   [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

Pyrocatechin \Pyr`o*cat"e*chin\, n. [Pyro- + catechu.] (Chem.)
   A white crystalline substance, {C6H4(OH)2}, of the phenol
   series, found in various plants; -- so called because first
   obtained by distillation of gum catechu. Called also
   {catechol}, {oxyphenol}. etc.
   [1913 Webster]

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