1,3-Dihydroxynaphthalene

1,3-Dihydroxynaphthalene
Names
	Other names naphthoresorcinol, 1,3-naphthalenediol
Identifiers
CAS Number	132-86-5 ;
3D model (JSmol)	Interactive image;
ChEMBL	ChEMBL381547;
ChemSpider	8282;
ECHA InfoCard	100.004.619
EC Number	205-079-7;
PubChem CID	8601;
UNII	5X457YEW8Y;
CompTox Dashboard (EPA)	DTXSID8059631 ;
	InChI InChI=1S/C10H8O2/c11-8-5-7-3-1-2-4-9(7)10(12)6-8/h1-6,11-12H Key: XOOMNEFVDUTJPP-UHFFFAOYSA-N;
	SMILES C1=CC=C2C(=C1)C=C(C=C2O)O;
Properties
Chemical formula	C10H8O2
Molar mass	160.172 g·mol−1
Appearance	colorless or white solid
Melting point	122–124 °C (252–255 °F; 395–397 K)
Hazards
	GHS labelling:[1]
Pictograms
Signal word	Warning
Hazard statements	H315, H319, H335, H341
Precautionary statements	P203, P261, P264, P264+P265, P271, P280, P302+P352, P304+P340, P305+P351+P338, P318, P319, P321, P332+P317, P337+P317, P362+P364, P403+P233, P405, P501
Flash point	Ethyl phenylacetylmalonate.z
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

1,3-Dihydroxynaphthalene is an organic compound with the formula C₁₀H₆(OH)₂. It is one of several isomers of dihydroxynaphthalene.

It can be prepared by hydrolysis of 1,3-diaminonaphthalene. An alternative laboratory route is decarboxylation of 1,3-dihydroxynaphthalene-2-carboxylic acid, which in turn is obtained by cyclization of esters of phenylacetylmalonate.

The compound attracted some interest because its conjugate base exists as the dionate tautomer:

The pKa of 1,3-dihydroxynaphthalene is 7.35, which is anomalous compared to the pKa's of phenol and 1-naphthol, which are respectively 9.95 and 9.85. This anomaly is explained by the tautomerism.