Bromine

Athanor · official

Br₂ · 159.81 g/mol

IUPAC name: molecular bromine

Also called dibromine

Inorganic

Open in Athanor

Drawn from its SMILES with RDKit

DangerCauses severe skin burns and eye damage · Fatal if inhaled · Very toxic to aquatic life

Names and identifiers

IUPAC name: molecular bromine
Synonyms: dibromine, Dibromine, molecular bromine
+ 36 more
Brom, Brome, Bromo, Broom, dibromane, SBV4XY874G, BROMIUM, DTXSID1035238, CHEBI:29224, Bromine 79, Total Bromine, Bromium 6C, Bromium 30C, RefChem:6397, DTXCID9015238, 231-778-1, Br, Bromine-79, CHEBI:33117, D-149, MFCD00010896, Br2, Bromo [Italian], Bromo [Spanish], Brome [French], Brom [German], Broom [Dutch], Caswell No. 112, Bromoniumbromid, bromine-bromide, Bromine liquid, Diatomic bromine, HSDB 514, bromo-, Bromine water, CP, EINECS 231-778-1
Molecular formula: Br₂
Empirical formula: Br
Molecular weight: 159.81 g/mol
Exact mass: 159.83463
CAS number: 7726-95-6
PubChem CID: 24408
Canonical SMILES: BrBr
Isomeric SMILES: BrBr
InChI: InChI=1S/Br2/c1-2
InChIKey: GDTBXPJZTBHREO-UHFFFAOYSA-N
Molfile

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

Physical properties

TemperaturePressureDensity

Appearance: Dense, dark red, mobile liquid; vaporizes readily at room temperature to give a red vapor[6]
7 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– Bromine is a dark reddish-brown fuming liquid with a pungent odor. Denser than water and soluble in water. Hence sinks in water. Toxic by inhalation. Accelerates the burning of combustible material. It is very corrosive to tissue and to metals. [1] CAMEO Chemicals
– Bromine, solution appears as a reddish-brown aqueous solution. The solubility of bromine in water equals 0.33 mg/ mL. [1] CAMEO Chemicals
– Liquid [2] EPA Chemical Data Reporting (CDR)
– FUMING RED-TO-BROWN LIQUID WITH PUNGENT ODOUR. [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– Dark reddish-brown, fuming liquid with suffocating, irritating fumes. [4] Occupational Safety and Health Administration (OSHA)
– Dark reddish-brown, fuming liquid with suffocating, irritating fumes. [5] The National Institute for Occupational Safety and Health (NIOSH)
–shown Dense, dark red, mobile liquid; vaporizes readily at room temperature to give a red vapor [6] Hazardous Substances Data Bank (HSDB)cites Grinbaum B, Freiberg M; Bromine. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2014). New York, NY: John Wiley & Sons. Online Posting Date: Oct 14, 2011.
Odor: Bleachy, penetrating[6]
Melting point: -7.2 °C[3]
5 values
5 of 5 sources agree on it (most common value).
Value As written Source
−7 °C 19 °F (EPA, 1998) [1] CAMEO Chemicalscites U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
−7.2 °Cshown -7.2 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
−7 °C 19 °F [4] Occupational Safety and Health Administration (OSHA)
−7.2 °C -7.2 °C [7] PAC Chemical Database, U.S. Department of Energy
−7 °C 19 °F [5] The National Institute for Occupational Safety and Health (NIOSH)
Boiling point: 59.6 °C (139.2 °F) at 760 mmHg (EPA, 1998)[1]
5 values
5 of 5 sources agree on it (most common value).
Value As written Source
59.6 °Cshown 139.2 °F at 760 mmHg (EPA, 1998) [1] CAMEO Chemicalscites U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
58.8 °C 58.8 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
59 °C 139 °F [4] Occupational Safety and Health Administration (OSHA)
58.8 °C 58.8 °C @760 [mm Hg] [7] PAC Chemical Database, U.S. Department of Energy
59 °C 139 °F [5] The National Institute for Occupational Safety and Health (NIOSH)
Density: 3.1028 @25 °C[7]
5 values
5 of 5 sources agree on it (most common value).
Value As written Source
– 3.1023 at 77 °F (EPA, 1998) - Denser than water [1] CAMEO Chemicalscites U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
– Relative density (water = 1): 3.1 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– 3.1023 [4] Occupational Safety and Health Administration (OSHA)
–shown 3.1028 @25 °C [7] PAC Chemical Database, U.S. Department of Energy
– 3.12 [5] The National Institute for Occupational Safety and Health (NIOSH)
1 more value was reported but failed the checks (unreadable or out of range), so it is not shown.
Solubility in water: Solubility in water, g/100ml at 20 °C: 4.0[3]
6 values
From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.
Value As written Source
– 4 % (NIOSH, 2024) [1] CAMEO Chemicals
– In water, 33.6 g/L at 25 °C [6] Hazardous Substances Data Bank (HSDB)cites Grinbaum B, Freiberg M; Bromine. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2014). New York, NY: John Wiley & Sons. Online Posting Date: Oct 14, 2011.
– Water solubility: 35.8 g/L at 20 °C; 41.7 g/L at 0 °C [6] Hazardous Substances Data Bank (HSDB)cites European Commission; IUCLID Dataset, Bromine CAS No. 7726-95-6 (Feb 19, 2000); Eurpoean Chemicals Bureau; Available from, as of Oct 10, 2014: https://esis.jrc.ec.europa.eu/doc/IUCLID/datasheet/7726956.pdf
– Bromine is soluble in nonpolar solvents and in certain polar solvents such as alcohol and sulfuric acid. It is miscible with ... many halogenated solvents. [6] Hazardous Substances Data Bank (HSDB)cites Grinbaum B, Freiberg M; Bromine. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2014). New York, NY: John Wiley & Sons. Online Posting Date: Oct 14, 2011.
–shown Solubility in water, g/100ml at 20 °C: 4.0 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– 4% [5] The National Institute for Occupational Safety and Health (NIOSH)
Vapor pressure: 172 mmHg at 20.60 °C (69.08 °F, EPA 1998)[1]
4 values
2 of 4 sources agree on it (most common value).
Value As written Source
172 mmHgshown 172 mmHg at 69.08 °F (EPA, 1998) [1] CAMEO Chemicalscites U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
212 mmHg 212 mm Hg at 25 °C [6] Hazardous Substances Data Bank (HSDB)cites Daubert, T.E., R.P. Danner. Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis, 1989.
170 mmHg Vapor pressure, kPa at 20 °C: 23.3 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
75 mmHg 75 [mm Hg] @2.5 °C [7] PAC Chemical Database, U.S. Department of Energy
2 more values were reported but failed the checks (unreadable or out of range), so they are not shown.
Autoignition temperature: Reported, but no value passed the checks.
The value and why
Not flammable (USCG, 1999) (could not be read; source [1])
Viscosity: Reported, but no value passed the checks.
The 5 values and why
0.134 cSt at 20 °C (could not be read; source [6])
0.288 cSt at 30 °C (could not be read; source [6])
0.264 cSt at 40 °C (could not be read; source [6])
0.245 at 50 °C (could not be read; source [6])
0.264 mm²/s at 40 °C (could not be read; source [3])
Refractive index: Index of refraction = 1.6083 at 20 °C[6]
2 values
Only one source reports it.
Value As written Source
–shown Index of refraction = 1.6083 at 20 °C [6] Hazardous Substances Data Bank (HSDB)cites Grinbaum B, Freiberg M; Bromine. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2014). New York, NY: John Wiley & Sons. Online Posting Date: Oct 14, 2011.
– 1.6478 at 25 °C [6] Hazardous Substances Data Bank (HSDB)cites Grinbaum B, Freiberg M; Bromine. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2014). New York, NY: John Wiley & Sons. Online Posting Date: Oct 14, 2011.

Value	As written	Source
–	Bromine is a dark reddish-brown fuming liquid with a pungent odor. Denser than water and soluble in water. Hence sinks in water. Toxic by inhalation. Accelerates the burning of combustible material. It is very corrosive to tissue and to metals.	[1] CAMEO Chemicals
–	Bromine, solution appears as a reddish-brown aqueous solution. The solubility of bromine in water equals 0.33 mg/ mL.	[1] CAMEO Chemicals
–	Liquid	[2] EPA Chemical Data Reporting (CDR)
–	FUMING RED-TO-BROWN LIQUID WITH PUNGENT ODOUR.	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	Dark reddish-brown, fuming liquid with suffocating, irritating fumes.	[4] Occupational Safety and Health Administration (OSHA)
–	Dark reddish-brown, fuming liquid with suffocating, irritating fumes.	[5] The National Institute for Occupational Safety and Health (NIOSH)
–shown	Dense, dark red, mobile liquid; vaporizes readily at room temperature to give a red vapor	[6] Hazardous Substances Data Bank (HSDB)cites Grinbaum B, Freiberg M; Bromine. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2014). New York, NY: John Wiley & Sons. Online Posting Date: Oct 14, 2011.

Value	As written	Source
−7 °C	19 °F (EPA, 1998)	[1] CAMEO Chemicalscites U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
−7.2 °Cshown	-7.2 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
−7 °C	19 °F	[4] Occupational Safety and Health Administration (OSHA)
−7.2 °C	-7.2 °C	[7] PAC Chemical Database, U.S. Department of Energy
−7 °C	19 °F	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
59.6 °Cshown	139.2 °F at 760 mmHg (EPA, 1998)	[1] CAMEO Chemicalscites U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
58.8 °C	58.8 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
59 °C	139 °F	[4] Occupational Safety and Health Administration (OSHA)
58.8 °C	58.8 °C @760 [mm Hg]	[7] PAC Chemical Database, U.S. Department of Energy
59 °C	139 °F	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
–	3.1023 at 77 °F (EPA, 1998) - Denser than water	[1] CAMEO Chemicalscites U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
–	Relative density (water = 1): 3.1	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	3.1023	[4] Occupational Safety and Health Administration (OSHA)
–shown	3.1028 @25 °C	[7] PAC Chemical Database, U.S. Department of Energy
–	3.12	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
–	4 % (NIOSH, 2024)	[1] CAMEO Chemicals
–	In water, 33.6 g/L at 25 °C	[6] Hazardous Substances Data Bank (HSDB)cites Grinbaum B, Freiberg M; Bromine. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2014). New York, NY: John Wiley & Sons. Online Posting Date: Oct 14, 2011.
–	Water solubility: 35.8 g/L at 20 °C; 41.7 g/L at 0 °C	[6] Hazardous Substances Data Bank (HSDB)cites European Commission; IUCLID Dataset, Bromine CAS No. 7726-95-6 (Feb 19, 2000); Eurpoean Chemicals Bureau; Available from, as of Oct 10, 2014: https://esis.jrc.ec.europa.eu/doc/IUCLID/datasheet/7726956.pdf
–	Bromine is soluble in nonpolar solvents and in certain polar solvents such as alcohol and sulfuric acid. It is miscible with ... many halogenated solvents.	[6] Hazardous Substances Data Bank (HSDB)cites Grinbaum B, Freiberg M; Bromine. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2014). New York, NY: John Wiley & Sons. Online Posting Date: Oct 14, 2011.
–shown	Solubility in water, g/100ml at 20 °C: 4.0	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	4%	[5] The National Institute for Occupational Safety and Health (NIOSH)

Value	As written	Source
172 mmHgshown	172 mmHg at 69.08 °F (EPA, 1998)	[1] CAMEO Chemicalscites U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
212 mmHg	212 mm Hg at 25 °C	[6] Hazardous Substances Data Bank (HSDB)cites Daubert, T.E., R.P. Danner. Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis, 1989.
170 mmHg	Vapor pressure, kPa at 20 °C: 23.3	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
75 mmHg	75 [mm Hg] @2.5 °C	[7] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
–shown	Index of refraction = 1.6083 at 20 °C	[6] Hazardous Substances Data Bank (HSDB)cites Grinbaum B, Freiberg M; Bromine. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2014). New York, NY: John Wiley & Sons. Online Posting Date: Oct 14, 2011.
–	1.6478 at 25 °C	[6] Hazardous Substances Data Bank (HSDB)cites Grinbaum B, Freiberg M; Bromine. Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2014). New York, NY: John Wiley & Sons. Online Posting Date: Oct 14, 2011.

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: 2
Rings: 0
Aromatic rings: 0
Fraction sp³ carbons (Fsp3): 0
H-bond donors: 0
H-bond acceptors: 0
Rotatable bonds: 0
TPSA (Å²): 0
Formal charge: 0
XLogP3: 1.9 PubChem
Complexity: 0 PubChem
Stereocenters: None
Double-bond geometry: None specified
Point group: D∞h of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

Br100.00%

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: 1.69 Crippen (Wildman and Crippen 1999)
log S (water solubility): -1.9 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 4.39 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 159.81
log P ≤ 5 (Crippen): 1.69
H-bond donors ≤ 5: 0
H-bond acceptors ≤ 10: 0

Passes all four rules.

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 [8].

Corrosive
Acute toxicity
Environmental hazard

NFPA 704[4]

H314Causes severe skin burns and eye damage
H330Fatal if inhaled
H400Very toxic to aquatic life

Precautionary statements: P260, P264, P271, P273, P280, P284, P301+P330+P331, P302+P361+P354, P304+P340, P305+P354+P338, P316, P320, P321, P363, P391, P403+P233, P405, P501

View all classifications (4)

[8] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · DangerH314, H330, H400
[9] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for 0.1% (1 of 725) of reports.
[9] European Chemicals Agency (ECHA) · 725 reports · DangerH314, H318, H330, H400
[6] Hazardous Substances Data Bank (HSDB) · DangerH314, H318, H330, H400

Exposure limits

PEL-TWA (8-Hour Time Weighted Average): 0.1 ppm (0.7 mg/m³)[4]
PEL: TWA 0.1 ppm (0.7 mg/m3) See Appendix G[5]
REL-STEL (Short Term Exposure Limit): 0.3 ppm (2 mg/m³)[4]
REL: TWA 0.1 ppm (0.7 mg/m3) ST 0.3 ppm (2 mg/m3)[5]
TLV: 0.1 ppm as TWA; 0.2 ppm as STEL.[3]
IDLH: 3 ppm (NIOSH, 2024)[1]

First aid

Warning: Effects may be delayed for several hours. Caution is advised. Signs and Symptoms of Acute Bromine Exposure: Signs and symptoms of acute exposure to bromine may include hypotension (low blood pressure), tachycardia (rapid heart rate), cyanosis (blue tint to the skin and mucous membranes), and circulatory collapse. Neurological effects may include headache, dizziness, delirium, stupor, and shock. Gastrointestinal effects may include vomiting (vomitus may be blue), diarrhea, abdominal pain, and bloody stools.[1]
Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]: Refer to the "General First Aid" section. Specific First Aid: For corrosives, in case of contact, immediately flush skin or eyes with running water for at least 30 minutes. Additional flushing may be required. (ERG, 2024)[1]
General First Aid: · Call 911 or emergency medical service. · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination. · Move victim to fresh air if it can be done safely. · Administer oxygen if breathing is difficult. · If victim is not breathing: -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance. -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped…[10]
(General first aid procedures) Eye: Irrigate immediately - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately. Skin: Soap wash immediately - If this chemical contacts the skin, immediately wash the contaminated skin with soap and water.[5]

Storage

Provision to contain effluent from fire extinguishing. Separated from food and feedstuffs. See Chemical Dangers. Cool. Dry. Well closed. Keep in a well-ventilated room. Store only in original container. Store in an area without drain or sewer access.[3]
Conditions for safe storage, including any incompatibilities: Keep container tightly closed in a dry and well-ventilated place. Containers which are opened must be carefully resealed and kept upright to prevent leakage. Do not store in polyethylene containers. Handle and open container with care.[6]
Storage Recommendations: Store in cool, dry, well-venilated location. Separate from oxidizing materials.[6]

Incompatibilities

During bromination of acetone to bromoacetone, presence of a large excess of bromine must be avoided to prevent sudden and violent reaction.[6]
Organic cmpd containing active hydrogen atoms adjacent to a carbonyl group (aldehydes, ketones, carboxylic acids) may react violently in unmoderated contact with bromine.[6]
Interaction of (bromine and diethyl zinc) without diluents may produce dangerous explosions ...[6]
Lithium is stable in contact with dry bromine, but heavy impact will initiate explosion, while sodium in contact with bromine needs only moderate impact for initiation. Potassium ignites in bromine vapor and explodes violently in contact with liquid bromine and rubidium ignites in bromine vapor. Aluminum, mercury, or titanium react violently with dry bromine. Warm germanium ignites in bromine vapor and antimony ignites in bromine vapor and reacts explosively with the liquid halogen.[6]

Safety data sheets on the supplier’s page: VladaChem, MuseChem, Thermo Fisher Scientific.

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

Spectra

GC-MSNIST Mass Spectrometry Data Center

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]CAMEO Chemicals · Public domain (NOAA) · via PubChem · retrieved 2026-10-14
[2]EPA Chemical Data Reporting (CDR) · Public domain (US EPA) · via PubChem · retrieved 2026-10-14
[3]ILO-WHO International Chemical Safety Cards (ICSCs) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
[4]Occupational Safety and Health Administration (OSHA) · Public domain (US DOL) · via PubChem · retrieved 2026-10-14
[5]The National Institute for Occupational Safety and Health (NIOSH) · Public domain (US CDC) · via PubChem · retrieved 2026-10-14
[6]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
[7]PAC Chemical Database, U.S. Department of Energy · Public domain (US DOE) · via PubChem · retrieved 2026-10-14
[8]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
[9]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
[10]Emergency Response Guidebook (ERG) · Public domain (US DOT) · via PubChem · retrieved 2026-10-14
[11]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.