Boron tribromide
[CAS# 10294-33-4]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Boride, borate and perborate
• Name: Boron tribromide
• Synonyms: ethyl 6-decoxy-7-ethoxy-4-oxo-1H-quinoline-3-carboxylate
• Molecular Formula: BBr₃
• Molecular Weight: 250.52
• CAS Registry Number: 10294-33-4
• EC Number: 233-657-9
• SMILES: B(Br)(Br)Br

Properties

• Solubility: Decomp.
• Density: 2.645 g/mL (4 °C)
• Melting point: -46 °C
• Boiling point: 91.2-91.4 °C (101325 mmHg)
• Flash point: -4 °C

Safety Data

• Hazard Symbols: GHS06;GHS05 Danger
• Risk Statements: H330-H300-H314
• Safety Statements: S9;S26;S28;S36/37/39;S45

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin corrosion	Skin Corr.	1A	H314
Acute toxicity	Acute Tox.	2	H300
Acute toxicity	Acute Tox.	2	H330
Flammable liquids	Flam. Liq.	4	H227

• Transport Information: UN 2629

Discovery and Applications

Boron tribromide was first synthesized and characterized in the late 19th century and is prepared by reacting boron trichloride (BCl3) with bromine (Br2). The compound is a colorless to pale yellow liquid at room temperature and pressure with a strong pungent odor. Due to the presence of the boron-bromine bond, it is highly reactive and loses valuable reagents in organic chemistry.

Boron tribromide is known for its Lewis acidity, which is attributed to the electron deficiency of boron. It readily accepts electron pairs from donor molecules, acting as a strong Lewis acid in various chemical reactions. In addition to its liquid state, BBr3 can also form complexes with Lewis bases, which alter its reactivity and enhance its usefulness in specific syntheses.

Boron tribromide is commonly used in the selective halogenation of organic compounds, replacing hydrogen atoms in aromatic and aliphatic structures with bromine atoms. This process is essential for the synthesis of pharmaceuticals, agrochemicals, and specialty chemicals that require precise modifications of molecular structures.

As a Lewis acid catalyst, BBr3 promotes esterification and acylation reactions by activating carbonyl compounds such as carboxylic acids and acyl chlorides. This ability is important in the production of esters, which are essential ingredients in fragrance synthesis, polymer chemistry, and pharmaceutical manufacturing.

Boron tribromide acts as an initiator in certain polymerization processes, particularly in the production of synthetic rubbers and elastomers. It promotes the formation of polymer chains by initiating reactions between monomers, resulting in materials with specific mechanical and chemical properties.

Boron tribromide is highly reactive and corrosive, posing a significant hazard to human health and the environment. Proper handling procedures must be followed when storing and working with boron tribromide in a laboratory setting, including the use of a fume hood, protective clothing, and neutralization protocols. Because boron tribromide is reactive with moisture and air, it should be stored in anhydrous conditions and handled with care to prevent accidental exposure or release.

References

2024. Preparation of arylboronic and diarylborinic acids from potassium aryl(fluoro)borates. Monatshefte für Chemie - Chemical Monthly, 155(6).
DOI: 10.1007/s00706-024-03213-4

2024. Design and synthesis of diphenyl-1H-imidazole analogs targeting Mpro/3CLpro enzyme of SARS-CoV-2. Medicinal Chemistry Research, 33(7).
DOI: 10.1007/s00044-024-03263-7

2024. A synthetic curcumin-like diarylpentanoid analog inhibits rhinovirus infection in H1 hela cells via multiple antiviral mechanisms. Daru: Journal of Faculty of Pharmacy, Tehran University of Medical Sciences, 32(2).
DOI: 10.1007/s40199-024-00542-x