2,5-Dihydroxy-1,4-benzoquinone or 2,5-dihydroxy-para-benzoquinone is an organic compound with formula C
4, formally derived from 1,4-benzoquinone by replacing two hydrogen atoms with hydroxyl (OH) groups. It is one of seven dihydroxybenzoquinone isomers. It is a yellow solid with planar molecules that exhibits ferroelectric properties.
The compound is a weak acid: one or both hydroxyls can lose a proton to yield the anions C
4 (pKa1 = 2.95) and C
4 (pKa2 = 4.87), respectively. The latter forms a variety of metal complexes, functioning as a binucleating ligand.
The compound has been identified as partly responsible for the color of aged cellulosic materials.