Benzoquinonetetracarboxylic acid

In chemistry, 1,4-benzoquinonetetracarboxylic acid is an organic compound with formula C10H4O10, or (C6O2)(-(CO)OH)4, which can be viewed as deriving from para-benzoquinone C6H4O2 through replacement of the four hydrogen atoms by carboxyl functional groups -(CO)OH. By removal of four protons, the acid is expected to yield the anion C10O4−10, benzoquinonetetracarboxylate, which is one of the oxocarbon anions (consisting solely of oxygen and carbon). By loss of 1 through 3 protons, it forms the anions C10H3O−10, C10H2O2−10, and C10HO3−10, called respectively trihydrogen-, dihydrogen-, and hydrogenbenzoquinonetetracarboxylate.

Source: Wikipedia — Benzoquinonetetracarboxylic acid (CC BY-SA 4.0)