Hydroquinone

It looks like this:

           H
           |
           C
         /   \
    H - C     C - O - H
        |  O  |
H - O - C     C - H
         \   /
           C
           |
           H

Other assorted data: it can brown apples and is one of the chemicals used by the bombardier beetle in its defence system. rp informs me that it is also used as a whitener in body milk.

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.

© Webster 1913.