2,5-Dihydroxy-1,4-benzoquinone

2,5-Dihydroxy-1,4-benzoquinone
Names
	Preferred IUPAC name 2,5-Dihydroxycyclohexa-2,5-diene-1,4-dione
	Other names 2,5-Dihydroxybenzoquinone; 2,5-Dihydroxy-p-benzoquinone; Anilic acid;
Identifiers
CAS Number	615-94-1 ;
3D model (JSmol)	Interactive image; Interactive image;
ChemSpider	62426 ;
ECHA InfoCard	100.009.505
PubChem CID	69213;
UNII	0KG5HVB52Z ;
CompTox Dashboard (EPA)	DTXSID4060658 ;
	InChI InChI=1S/C6H4O4/c7-3-1-4(8)6(10)2-5(3)9/h1-2,7,10H Key: QFSYADJLNBHAKO-UHFFFAOYSA-N ; InChI=1/C6H4O4/c7-3-1-4(8)6(10)2-5(3)9/h1-2,7,10H Key: QFSYADJLNBHAKO-UHFFFAOYAW;
	SMILES C1=C(C(=O)C=C(C1=O)O)O; O=C\1C(\O)=C/C(=O)C(/O)=C/1;
Properties
Chemical formula	C6H4O4
Molar mass	140.094 g·mol−1
Appearance	yellow solid
Melting point	210 to 212 °C (410 to 414 °F; 483 to 485 K)
Acidity (pKa)	pKa1 = 2.71; pKa2 = 5.18
Hazards
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302, H312, H315, H319, H332, H335
Precautionary statements	P261, P264, P264+P265, P270, P271, P280, P301+P317, P302+P352, P304+P340, P305+P351+P338, P317, P319, P321, P330, P332+P317, P337+P317, P362+P364, P403+P233, P405, P501
Related compounds
Related compounds	Hydroxy-1,4-benzoquinone; Tetrahydroxy-1,4-benzoquinone;
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

2,5-Dihydroxy-1,4-benzoquinone or 2,5-dihydroxy-para-benzoquinone is an organic compound with chemical formula C
₆H
₄O
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
₆H
₃O⁻
₄ (pK_a1 = 2.71) and C
₆H
₂O²⁻
₄ (pK_a2 = 5.18), 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.