Ethidium bromide

Athanor · official

C₂₁H₂₀BrN₃ · 394.3 g/mol

IUPAC name: 5-ethyl-6-phenylphenanthridin-5-ium-3,8-diamine bromide

Also called EtBr, EB, homidium bromide, gel stain, intercalator

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Drawn from its SMILES with RDKit

DangerHarmful if swallowed · Fatal if inhaled · Suspected of causing genetic defects

Names and identifiers

IUPAC name: 5-ethyl-6-phenylphenanthridin-5-ium-3,8-diamine bromide
Synonyms: EtBr, EB, homidium bromide
+ 39 more
gel stain, intercalator, Homidium bromide, Dromilac, 3,8-Diamino-5-ethyl-6-phenylphenanthridinium bromide, Ethydium bromide, Bromure d'homidium, Bromuro de homidio, Homidii bromidum, 2,7-Diamino-10-ethyl-9-phenylphenanthridinium bromide, 2,7-Diamino-9-phenyl-10-ethylphenanthridinium bromide, 2,7-Diamino-9-phenylphenanthridine ethobromide, DTXSID8025258, NSC-268986, RD 1572, 059NUO2Z1L, CHEBI:4883, DTXCID605258, Bromide, Ethidium, Bromide, Homidium, RefChem:138396, 214-984-6, 3,8-Diamino-5-ethyl-6-phenylphenanthridin-5-ium bromide, Phenanthridinium, 3,8-diamino-5-ethyl-6-phenyl-, bromide, Ethidium (bromide), Ethidium bromide(EB), Phenanthridinium, 3,8-diamino-5-ethyl-6-phenyl-, bromide (1:1), 5-ethyl-6-phenylphenanthridin-5-ium-3,8-diamine;bromide, MLS002702536, NSC268986, NCGC00091387-01, NCGC00095070-01, CHEMBL284328, Homidium bromide [INN:BAN], CAS-1239-45-8, Homidii bromidum [INN-Latin], CCRIS 1017, HSDB 7297, Bromure d'homidium [INN-French]
Molecular formula: C₂₁H₂₀BrN₃
Empirical formula: C₂₁H₂₀BrN₃
Molecular weight: 394.3 g/mol
Exact mass: 393.08406
CAS number: 1239-45-8
PubChem CID: 14710
Canonical SMILES: CC[N+]1=C2C=C(C=CC2=C3C=CC(=CC3=C1C4=CC=CC=C4)N)N.[Br-]
Isomeric SMILES: CC[N+]1=C2C=C(C=CC2=C3C=CC(=CC3=C1C4=CC=CC=C4)N)N.[Br-]
InChI: InChI=1S/C21H19N3.BrH/c1-2-24-20-13-16(23)9-11-18(20)17-10-8-15(22)12-19(17)21(24)14-6-4-3-5-7-14;/h3-13,23H,2,22H2,1H3;1H
InChIKey: ZMMJGEGLRURXTF-UHFFFAOYSA-N
Molfile

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

Physical properties

TemperaturePressureDensity

Appearance: Maroon powder[2]
2 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– RED-TO-BROWN CRYSTALS. [1] ILO-WHO International Chemical Safety Cards (ICSCs)
–shown Maroon powder [2] Hazardous Substances Data Bank (HSDB)cites Green FJ; The Sigma-Aldrich Handbook of Stains, Dyes and Indicators. Milwaukee, WI: Aldrich Chemical Company, Inc., p. 318 (1990)
Melting point: 238-240 °C[1]
2 values
Sources disagree; from ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative.
Value As written Source
260 to 262 °C 260-262 °C (decomposes) [2] Hazardous Substances Data Bank (HSDB)cites Green FJ; The Sigma-Aldrich Handbook of Stains, Dyes and Indicators. Milwaukee, WI: Aldrich Chemical Company, Inc., p. 318 (1990)
238 to 240 °Cshown 238-240 °C [1] ILO-WHO International Chemical Safety Cards (ICSCs)
Density: 0.34 g/cm³[1]
Solubility in water: Solubility in water, g/100ml at 20 °C: 5[1]
2 values
From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.
Value As written Source
– Solubility in 2-methoxyethanol is 20 mg/mL; ethanol, 2 mg/mL [2] Hazardous Substances Data Bank (HSDB)cites Green FJ; The Sigma-Aldrich Handbook of Stains, Dyes and Indicators. Milwaukee, WI: Aldrich Chemical Company, Inc., p. 318 (1990)
–shown Solubility in water, g/100ml at 20 °C: 5 [1] ILO-WHO International Chemical Safety Cards (ICSCs)
log P: -1.1[1]
2 values
Sources disagree; from ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative.
Value As written Source
– log Kow= -0.38 /Estimated/ [2] Hazardous Substances Data Bank (HSDB)cites US EPA; Estimation Program Interface (EPI) Suite. Ver.3.11. June 10, 2003. Available from, as of Sept 22, 2004: https://www.epa.gov/oppt/exposure/pubs/episuitedl.htm
–shown -1.1 [1] ILO-WHO International Chemical Safety Cards (ICSCs)
Vapor pressure: 1.2 × 10⁻¹² mmHg at 25 °C (estimated)[2]
Flash point: >100 °C[1]

Value	As written	Source
–	RED-TO-BROWN CRYSTALS.	[1] ILO-WHO International Chemical Safety Cards (ICSCs)
–shown	Maroon powder	[2] Hazardous Substances Data Bank (HSDB)cites Green FJ; The Sigma-Aldrich Handbook of Stains, Dyes and Indicators. Milwaukee, WI: Aldrich Chemical Company, Inc., p. 318 (1990)

Value	As written	Source
260 to 262 °C	260-262 °C (decomposes)	[2] Hazardous Substances Data Bank (HSDB)cites Green FJ; The Sigma-Aldrich Handbook of Stains, Dyes and Indicators. Milwaukee, WI: Aldrich Chemical Company, Inc., p. 318 (1990)
238 to 240 °Cshown	238-240 °C	[1] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
–	Solubility in 2-methoxyethanol is 20 mg/mL; ethanol, 2 mg/mL	[2] Hazardous Substances Data Bank (HSDB)cites Green FJ; The Sigma-Aldrich Handbook of Stains, Dyes and Indicators. Milwaukee, WI: Aldrich Chemical Company, Inc., p. 318 (1990)
–shown	Solubility in water, g/100ml at 20 °C: 5	[1] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
–	log Kow= -0.38 /Estimated/	[2] Hazardous Substances Data Bank (HSDB)cites US EPA; Estimation Program Interface (EPI) Suite. Ver.3.11. June 10, 2003. Available from, as of Sept 22, 2004: https://www.epa.gov/oppt/exposure/pubs/episuitedl.htm
–shown	-1.1	[1] ILO-WHO International Chemical Safety Cards (ICSCs)

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: 25
Rings: 4
Aromatic rings: 4
Fraction sp³ carbons (Fsp3): 0.1
H-bond donors: 2
H-bond acceptors: 2 computed here · PubChem 3
Rotatable bonds: 2
TPSA (Å²): 55.9
Formal charge: 0
Complexity: 419 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

C63.97%
H5.11%
Br20.26%
N10.66%

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: 1.14 Crippen (Wildman and Crippen 1999)
log S (water solubility): -3.46 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 2.62 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 394.32
log P ≤ 5 (Crippen): 1.14
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

Harmonized EU classification (CLP Annex VI). Source [3].

Acute toxicity
Health hazard

H302Harmful if swallowed
H330Fatal if inhaled
H341Suspected of causing genetic defects

Precautionary statements: P203, P260, P264, P270, P271, P280, P284, P301+P317, P304+P340, P316, P318, P320, P330, P403+P233, P405, P501

View all classifications (2)

[3] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · DangerH302, H330, H341
[4] European Chemicals Agency (ECHA) · 34 reports · DangerH302, H330, H331, H341

Exposure limits

MAK (Maximale Arbeitsplatz Konzentration): Carcinogen category: 3; germ cell mutagen group: 3B[1]

First aid

Fresh air, rest.[1]
Rinse and then wash skin with water and soap.[1]
Rinse with plenty of water for several minutes (remove contact lenses if easily possible).[1]
Rinse mouth.[1]

Storage

Fireproof. Separated from strong oxidants and food and feedstuffs.[1]
Ethidium bromide should be handled in the laboratory using the "basic prudent practices" described in Chapter 5.C. Because of its mutagenicity, stock solutions of this compound should be prepared in a fume hood, and protective gloves should be worn at all times while handling this substance. Operations capable of generating ethidium bromide dust or aerosols of ethidium bromide solutions should be conducted in a fume hood to prevent exposure by inhalation.[2]

Safety data sheets on the supplier’s page: AppChem, Accel Scientific, LGC Standards.

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]ILO-WHO International Chemical Safety Cards (ICSCs) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
[2]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
[3]Regulation (EC) No 1272/2008 of the European Parliament and of the Council · EU reuse policy, CC BY 4.0 · via PubChem · retrieved 2026-10-14
[4]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
[5]SpectraBase · 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.