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Identity & molecular properties

Source-linked values

CAS number	123-31-9	ChEBI ↗
Molecular formula	C₆H₆O₂	ChEBI ↗
Molar mass	110.112 g/mol	ChEBI ↗
Monoisotopic mass	110.03678 Da	ChEBI ↗
Formal charge	0	ChEBI ↗
ChEBI identifier	CHEBI:17594	ChEBI ↗

Cross-source molecular data

PubChem

Molar mass	110.11 g/mol	PubChem ↗
Exact mass	110.036779430 Da	PubChem ↗
Computed XLogP	0.6	PubChem ↗
Topological polar surface area (Å²)	40.5	PubChem ↗
H-bond donors	2	PubChem ↗
H-bond acceptors	2	PubChem ↗
Rotatable bonds	0	PubChem ↗

PubChem computed values are shown separately from the ChEBI record. An exact InChIKey match was used to connect the records. Molecular descriptors do not describe a supplied product’s purity, particle size or performance.

Names & structural identifiers

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Source preferred name

hydroquinone

IUPAC name

benzene-1,4-diol

InChIKey

QIGBRXMKCJKVMJ-UHFFFAOYSA-N

SMILES

Oc1ccc(O)cc1

InChI

InChI=1S/C6H6O2/c7-5-1-2-6(8)4-3-5/h1-4,7-8H

Names & synonyms

benzene-1,4-diol

Names are supplied by ChEBI. Trade names and related synonyms may describe a broader product context.

Classification & relationships

ChEBI ontology

benzenediolChEBI parent class · 17701 ↗hydroquinonesChEBI parent class · 24646 ↗

phenols organic molecular entity

Roles recorded in ChEBI

antioxidantcofactorcarcinogenic agentmouse metabolitehuman xenobiotic metaboliteEscherichia coli metaboliteskin lightening agent

Database role annotations describe reported biological or chemical roles; they are not product approvals or recommendations for use.

Safety classification · Japan

NITE / Japanese government

Japan · FY2012 source classification
Hydroquinone · 24B6513

Endpoint	Reported classification
Acute toxicity （Oral）	Category 4
Serious eye damage/eye irritation	Category 1
Skin sensitization	Category 1
Germ cell mutagenicity	Category 1B
Carcinogenicity	Category 2
Specific target organ toxicity - Single exposure	Category 1 (central nervous system)

Selected source-reported endpoints. Other endpoints, rationales and conditions remain in the original classification. Missing or unlisted information does not mean non-hazardous. This is not a global classification or transport decision.

Read the original NITE classification

Mass ↔ amount of substance

Calculated from sourced mass

Amount

Input unit

Equivalent amount

0.00908166 mol

Uses 110.112 g/mol from ChEBI. Assumes the substance described by this record; no purity or concentration correction is applied.

Elemental composition

Theoretical mass fractions

C

Carbon · 6 atoms

65.45%

O

Oxygen · 2 atoms

29.06%

H

Hydrogen · 6 atoms

5.49%

Calculated theoretical mass fractions from the reported formula and PubChem periodic-table atomic masses. These are not assay or purity results.

Research & patent references

Selected source associations

Carcinogenicity of a nephrotoxic metabolite of the "nongenotoxic" carcinogen hydroquinone. ↗Chemical research in toxicology · 2001 Jan · PMID 11170505

Synthesis of (-)-5,8-dihydroxy-3R-methyl-2R-(dipropylamino)-1,2,3,4-tetrahydronaphthalene: an inhibitor of beta-amyloid(1-42) aggregation. ↗Bioorganic & medicinal chemistry · 2002 Nov · PMID 12213471

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Sources & record history

Checked 27 Sep 2026

Identity, formula, mass, synonyms & ontologyEMBL-EBI ChEBI · CHEBI:17594

Release 255, 9 September 2026. ChEBI three-star (manually annotated) source entry. View original record ↗ · CC BY 4.0

Additional molecular descriptorsNCBI PubChem · CID 785 · retrieved 2026-09-27

PubCAS formats source data, connects references and computes explicitly labelled conversions. CAS cross-references are supplied by ChEBI; they do not constitute CAS verification or endorsement.

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