Histamine

Athanor · official

C₅H₉N₃ · 111.15 g/mol

IUPAC name: 2-(1H-imidazol-5-yl)ethanamine

Also called 2-(1H-imidazol-4-yl)ethanamine

Natural products Rings

Open in Athanor

Drawn from its SMILES with RDKit

DangerToxic if swallowed · Causes skin irritation · May cause an allergic skin reaction · Causes serious eye irritation · May cause allergy or asthma symptoms or breathing difficulties if inhaled · May cause respiratory irritation

Names and identifiers

IUPAC name: 2-(1H-imidazol-5-yl)ethanamine
Synonyms: 2-(1H-imidazol-4-yl)ethanamine, 2-(1H-imidazol-5-yl)ethanamine, Ergamine
+ 36 more
Ergotidine, 1H-Imidazole-4-ethanamine, 2-(4-Imidazolyl)ethylamine, 5-Imidazoleethylamine, Eramin, Theramine, Free histamine, beta-Aminoethylglyoxaline, beta-Aminoethylimidazole, 4-(2-Aminoethyl)-1H-imidazole, 4-Imidazoleethylamine, Imidazole-4-ethylamine, beta-Imidazolyl-4-ethylamine, Imidazole, 4-(2-aminoethyl)-, DTXSID4023125, CHEBI:18295, 2-[4-Imidazolyl]ethylamine, NSC-33792, DTXCID103125, 820484N8I3, 2-(3H-imidazol-4-yl)ethanamine, NSC33792, ALEROFF, RefChem:5888, 200-100-6, 2-(1H-Imidazol-4-yl)ethanamine, 2-(1H-imidazol-4-yl)ethan-1-amine, 2-Imidazol-4-ylethylamine, Histamine Base, Histamine, Free Base, Istamina, 1H-Imidazole-5-ethanamine, 2-(3H-Imidazol-4-yl)-ethylamine, Ethylamine, 2-imidazol-4-yl-, L-histamine, [3H]histamine
Molecular formula: C₅H₉N₃
Empirical formula: C₅H₉N₃
Molecular weight: 111.15 g/mol
Exact mass: 111.07965
CAS number: 51-45-6
PubChem CID: 774
Canonical SMILES: C1=C(NC=N1)CCN
Isomeric SMILES: C1=C(NC=N1)CCN
InChI: InChI=1S/C5H9N3/c6-2-1-5-3-7-4-8-5/h3-4H,1-2,6H2,(H,7,8)
InChIKey: NTYJJOPFIAHURM-UHFFFAOYSA-N
Molfile

Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.

Physical properties

Solubility in water: COLORLESS LONG PRISMATIC CRYSTALS; ODORLESS; 1 G SOL IN ABOUT 4 ML WATER; AQ SOLN IS ACID TO LITMUS; WHEN DRIED AT 105 °C FOR 2 HR, IT MELTS AT ABOUT 140 °C (PHOSPHATE)[1]

Each value as its source reports it, with the source's number after it (listed under References). Where several sources report a property, the row shows the value most of them agree on, the rule the app uses; open the values to see every one.

Calculated

Heavy atoms: 8
Rings: 1
Aromatic rings: 1
Fraction sp³ carbons (Fsp3): 0.4
H-bond donors: 2
H-bond acceptors: 2
Rotatable bonds: 2
TPSA (Å²): 54.7
Formal charge: 0
XLogP3: -0.7 PubChem
Complexity: 64 PubChem
Stereocenters: None
Double-bond geometry: None specified
Point group: C1 of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

C54.03%
H8.16%
N37.81%

Isotope pattern

Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.

Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.

Predicted

log P: -0.09 Crippen (Wildman and Crippen 1999)
log S (water solubility): -0.8 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 3.08 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 111.15
log P ≤ 5 (Crippen): -0.09
H-bond donors ≤ 5: 2
H-bond acceptors ≤ 10: 2

Passes all four rules.

¹³C NMR shifts, predicted

Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.

Safety

Danger

Most widely reported: 45 company reports to ECHA. Source [2].

Acute toxicity
Harmful or irritant
Health hazard

H301Toxic if swallowed (93.3% of reports)
H315Causes skin irritation (93.3% of reports)
H317May cause an allergic skin reaction (93.3% of reports)
H319Causes serious eye irritation (93.3% of reports)
H334May cause allergy or asthma symptoms or breathing difficulties if inhaled (93.3% of reports)
H335May cause respiratory irritation (93.3% of reports)

Precautionary statements: P233, P260, P261, P264, P264+P265, P270, P271, P272, P280, P284, P301+P316, P302+P352, P304+P340, P305+P351+P338, P319, P321, P330, P332+P317, P333+P317, P337+P317, P342+P316, P362+P364, P403, P403+P233, P405, P501

View all classifications (2)

[2] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for 6.7% (3 of 45) of reports.
[2] European Chemicals Agency (ECHA) · 45 reports · DangerH301, H315, H317, H319, H334, H335

Safety data sheets on the supplier’s page: MP Biomedicals, Enamine, J&H Chemical Co.,ltd.

Always read the supplier’s safety data sheet before working with it.

Spectra

Experimental spectra held by these sources; each link opens the source's own record.

Literature

Reading PubChem, OpenAlex and GSRS…

Bioactivity

Reading ChEMBL…

References

[1]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
[2]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
[3]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
[4]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
[5]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
[6]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
[7]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
·Literature on PubChem

Data last updated 2026-10-14.