Bromine trifluoride (7787-71-5) Physical and Chemical Properties
Bromine trifluoride
A highly reactive interhalogen fluorinating agent and ionizing inorganic solvent used in specialized industrial fluorination and synthesis operations.
| CAS Number | 7787-71-5 |
| Family | Interhalogen fluorides |
| Typical Form | Colorless to pale yellow liquid |
| Common Grades | EP |
Bromine trifluoride is an inorganic interhalogen compound of the halogen family, formally described by the molecular formula \(\ce{BrF3}\). Structurally it is a three-coordinate bromine(III) center bound to three fluorine atoms; the electronic geometry is derived from a trigonal bipyramidal arrangement with two lone pairs on bromine, leading to an observed T-shaped molecular geometry in the gas and molecular liquid phases. The combination of a highly electronegative ligand set and a polyvalent bromine center produces a molecule with strong polar character, a high electron affinity toward nucleophiles (notably fluoride acceptors/donors), and marked Lewis acidity in fluoride-transfer chemistries.
Chemically, \(\ce{BrF3}\) is a powerful fluorinating and oxidizing agent and functions as an ionizing inorganic solvent for fluoride chemistry. It is strongly hydrolytic and reactive with hydrogen-containing substrates: contact with water leads to vigorous hydrolysis and evolution of corrosive gases such as hydrogen fluoride and hydrogen bromide. These attributes also make \(\ce{BrF3}\) corrosive to many metals and organic materials and capable of violent or explosive reactions with combustible or hydrogen-containing compounds. Industrially, it is used where aggressive fluorination or formation of metal fluorides is required, including applications in uranium fluoride chemistry and specialized fluorination processes.
Common commercial grades reported for this substance include: EP.
Basic Physical Properties
Density
- Reported densities: 2.81 at 68 \(\mathrm{^\circ F}\) (USCG, 1999) — denser than water; will sink.
- Reported laboratory value: 2.8030 \(\mathrm{g}\,\mathrm{cm}^{-3}\) at 25 \(\mathrm{^\circ C}\).
Comments: The liquid density substantially exceeds that of water; bulk handling and containment must consider sinking and immersion behavior. Reported values above are experimental data reported for typical samples.
Melting or Decomposition Point
- Melting/solidification: 47.8 \(\mathrm{^\circ F}\) (USCG, 1999).
- Equivalent reported value: 8.77 \(\mathrm{^\circ C}\).
Comments: Solid \(\ce{BrF3}\) forms long prisms at low temperature. Thermal behavior is dominated by its strong intermolecular interactions and the energetics of phase change for a highly polar molecular liquid.
Solubility in Water
No conventional solubility value is appropriate: \(\ce{BrF3}\) reacts with water rather than dissolving benignly. Hydrolysis is vigorous and may be violent, producing hydrogen fluoride (HF), hydrogen bromide (HBr) and oxygen evolution; therefore aqueous “solubility” is superseded by destructive chemical reaction.
Solution pH (Qualitative Behavior)
Aqueous contact produces strong hydrohalic acids (HF, HBr) and secondary acidic species; pH is not a meaningful or safe descriptor for systems where \(\ce{BrF3}\) is present because hydrolysis is rapid and corrosive. Any aqueous exposure should be treated as strongly acidic and hazardous.
Chemical Properties
Acid–Base Behavior
Bromine trifluoride is not a Bronsted acid in the conventional sense but behaves as a strong Lewis acid/fluorinating agent. It can accept or donate fluoride in fluoride-transfer equilibria and acts as an oxidizer in redox processes. In fluoride-rich or coordinating media, dissociation to ionic species (see Molecular and Ionic Parameters) is chemically accessible; in protic environments it is immediately hydrolyzed, generating strongly acidic products.
Reactivity and Stability
- Highly reactive, strong oxidizer and fluorinating reagent.
- Reacts violently with water (explosive interaction reported), generating HF and HBr and evolving oxygen; fumes in air.
- Explosive or violent reactions with organic materials, many metals, ammonium halides, and a wide variety of reducing agents and hydrogen-containing substrates.
- Fumes and decomposition products are highly corrosive and toxic (HF, HBr); thermal decomposition during fire produces the same hazardous gases.
- Hygroscopic and air-sensitive: samples may fume and corrode metals on exposure. Handling and process design must assume rapid, exothermic reactivity toward moisture and organics; compatibility protocols for materials of construction and rigorous inert-atmosphere control are required.
Molecular and Ionic Parameters
Formula and Molecular Weight
- Molecular formula: \(\ce{BrF3}\).
- Molecular weight: 136.90.
Additional computed parameters (as reported): - Exact mass: 135.91355 - Monoisotopic mass: 135.91355 - XLogP3-AA: 2.6 - Topological polar surface area (TPSA): 0 - Complexity: 8 - Heavy atom count: 4 - Formal charge: 0 - Hydrogen bond donor count: 0 - Hydrogen bond acceptor count: 3 - Rotatable bond count: 0
Constituent Ions
- Neutral molecular species under standard conditions; no fixed constituent ions in pure molecular \(\ce{BrF3}\).
- In fluoride-rich or strongly coordinating media, \(\ce{BrF3}\) can undergo ionization equilibria to give species formally described in the literature of fluoride chemistry (e.g., cationic and anionic bromine fluoride fragments). In practical terms, ionic solvation and formation of fluoride complexes are central to its function as an ionizing inorganic solvent and fluoride-transfer reagent.
Identifiers and Synonyms
Registry Numbers and Codes
- CAS number: 7787-71-5
- Deprecated CAS: 12524-63-9
- European Community (EC) number: 232-132-1
- UN Number: 1746
- UN/NA shipping name: Bromine trifluoride
- UNII: BD697HEL7X
- DSSTox Substance ID: DTXSID70894170
- InChI:
InChI=1S/BrF3/c2-1(3)4 - InChIKey:
FQFKTKUFHWNTBN-UHFFFAOYSA-N - SMILES:
FBr(F)F
Synonyms and Common Names
Selected reported synonyms and labels that appear in supplier/regulatory listings: - bromine trifluoride - Bromine fluoride (BrF3) - trifluoro-λ3-bromane - BrF3 - Brominetrifluoride - UN-1746 - BD697HEL7X
(Only listed identifiers and synonyms shown above are taken from reported registry and depositor-supplied names.)
Industrial and Commercial Applications
Functional Roles and Use Sectors
- Potent fluorinating agent in inorganic and specialized organic syntheses.
- Ionizing inorganic solvent for fluoride-based reactions and for preparing higher fluorides of metals.
- Employed in processing steps of uranium chemistry, including formation of uranium hexafluoride during enrichment and reprocessing operations.
- Listed uses include oxidizer roles in high-energy systems and specialized propellant/oxidizer research contexts.
Typical Application Examples
- Direct fluorination of robust organic substrates and inorganic precursors where aggressive fluorination is required and can be controlled.
- Production and purification steps in the conversion of bromine- or metal-containing feedstocks to corresponding fluorides.
- As a reagent for laboratory-scale syntheses requiring an anhydrous, highly oxidizing fluoride medium. If no site-specific application summary is available, selection for use is driven by the combination of strong fluorinating power, ionizing solvent behavior for fluoride chemistry, and the capacity to form metal fluorides under controlled, inert conditions.
Safety and Handling Overview
Health and Environmental Hazards
- Extremely hazardous by inhalation and by contact: corrosive to skin, eyes and mucous membranes; can cause severe burns and permanent injury including blindness.
- Acute inhalation can produce severe upper respiratory tract irritation, pulmonary edema and death at high concentrations.
- Chronic exposures may lead to systemic halide accumulation and neurological effects associated with bromide.
- Decomposition or hydrolysis products (HF, HBr) are acutely toxic and highly corrosive.
- Reported IDLH: 12 ppm.
- Acute Exposure Guideline Levels (AEGLs) reported (ppm):
- 10 min: AEGL-1 = 0.12; AEGL-2 = 8.1; AEGL-3 = 84
- 30 min: AEGL-1 = 0.12; AEGL-2 = 3.5; AEGL-3 = 36
- 60 min: AEGL-1 = 0.12; AEGL-2 = 2.0; AEGL-3 = 21
- 4 hr: AEGL-1 = 0.12; AEGL-2 = 0.70; AEGL-3 = 7.3
- 8 hr: AEGL-1 = 0.12; AEGL-2 = 0.41; AEGL-3 = 7.3
- Fire and decomposition produce toxic/gas-phase corrosives; runoff may contaminate waterways.
Emergency measures and first aid must assume severe corrosive inhalation and contact injuries. Immediate medical attention is required for all significant exposures; decontamination with copious water and specialist medical management for HF/HBr injuries is standard.
Storage and Handling Considerations
- Store under dry, inert, and well-ventilated conditions away from moisture, acids, bases, halide salts, organics, combustibles, and incompatible metals and metal oxides.
- Avoid materials known to react violently (ammonium halides, antimony salts, many metals, organic matter). Use compatible containment materials and explosion-proof electrical fittings.
- Do not allow contact with water; containers exposed to heat may rupture or “rocket” due to pressure build-up from decomposition gases.
- For spills and fires: do not apply water directly to the material; use dry chemical agents (dry sand, soda ash, lime, carbon dioxide) for small surrounding fires and follow specialist emergency response procedures for large incidents. Cool exposed containers with water spray from a safe, remote position only to prevent container rupture, but avoid directing water onto the spilled substance.
- PPE: positive-pressure self-contained breathing apparatus (SCBA), full chemical-protective clothing, splash goggles and face protection; specialized respiratory protection for emergency responders.
- For detailed hazard, transport and regulatory information, users should refer to the product-specific Safety Data Sheet (SDS) and local legislation.
