Home/Chemicals/71-30-7

Chemical substance record

Cytosine

71-30-7C₄H₅N₃O111.104 g/mol

Organic/Inorganic Small MoleculeChEBI source record

An aminopyrimidine that is pyrimidin-2-one having the amino group located at position 4. — ChEBI

Safety references

Safety documents & references

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Identity & molecular properties

Source-linked values

CAS number	71-30-7	ChEBI ↗
Molecular formula	C₄H₅N₃O	ChEBI ↗
Molar mass	111.104 g/mol	ChEBI ↗
Monoisotopic mass	111.04326 Da	ChEBI ↗
Formal charge	0	ChEBI ↗
ChEBI identifier	CHEBI:16040	ChEBI ↗

Cross-source molecular data

PubChem

Molar mass	111.10 g/mol	PubChem ↗
Exact mass	111.043261792 Da	PubChem ↗
Computed XLogP	-1.7	PubChem ↗
Topological polar surface area (Å²)	67.5	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

cytosine

IUPAC name

4-aminopyrimidin-2(1H)-one

InChIKey

OPTASPLRGRRNAP-UHFFFAOYSA-N

SMILES

Nc1ccnc(=O)n1

InChI

InChI=1S/C4H5N3O/c5-3-1-2-6-4(8)7-3/h1-2H,(H3,5,6,7,8)

Names & synonyms

4-aminopyrimidin-2(1H)-one

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

Classification & relationships

ChEBI ontology

pyrimidine nucleobaseChEBI parent class · 26432 ↗pyrimidoneChEBI parent class · 38337 ↗aminopyrimidineChEBI parent class · 38338 ↗

organic heterocyclic compound organic molecular entity

Roles recorded in ChEBI

antineoplastic agentmouse metaboliteSaccharomyces cerevisiae metaboliteEscherichia coli metabolitehuman metabolite

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

Mass ↔ amount of substance

Calculated from sourced mass

Amount

Input unit

Equivalent amount

0.00900058 mol

Uses 111.104 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 · 4 atoms

43.24%

N

Nitrogen · 3 atoms

37.82%

O

Oxygen · 1 atom

14.40%

H

Hydrogen · 5 atoms

4.54%

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

A STUDY OF THE CROSS-REACTIVITY OF ANTIPURIN-6-OYL SERUM WITH DEOXYRIBONUCLEIC ACID (DNA). ↗The Journal of experimental medicine · 1965 Jan 1 · PMID 14253484

Annotation of the human adult urinary metabolome and metabolite identification using ultra high performance liquid chromatography coupled to a linear quadrupole ion trap-Orbitrap mass spectrometer. ↗Analytical chemistry · 2012 Aug 7 · PMID 22770225

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Sources & record history

Checked 27 Sep 2026

Identity, formula, mass, synonyms & ontologyEMBL-EBI ChEBI · CHEBI:16040

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

Additional molecular descriptorsNCBI PubChem · CID 597 · 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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