Boron trifluoride etherate
[CAS# 109-63-7]

Identification

• Classification: Chemical reagent >> Organic reagent >> Ether
• Name: Boron trifluoride etherate
• Synonyms: Boron trifluoride ethyl ether
• Molecular Formula: C₄H₁₀BF₃O
• Molecular Weight: 141.93
• CAS Registry Number: 109-63-7
• EC Number: 203-689-8
• SMILES: B(F)(F)F.CCOCC

Properties

• Density: 1.12
• Melting point: -60 °C
• Boiling point: 126 °C
• Refractive index: 1.3429-1.3449
• Flash point: 48 °C
• Water solubility: Reacts

Safety Data

• Hazard Symbols: GHS02;GHS05;GHS06;GHS07;GHS08 Danger
• Risk Statements: H226-H302+H332-H302-H314-H318-H330-H332-H372-H412
• Safety Statements: P210-P233-P240-P241-P242-P243-P260-P261-P264-P264+P265-P270-P271-P273-P280-P284-P301+P317-P301+P330+P331-P302+P361+P354-P303+P361+P353-P304+P340-P305+P354+P338-P316-P317-P319-P320-P321-P330-P363-P370+P378-P403+P233-P403+P235-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Specific target organ toxicity - repeated exposure	STOT RE	1	H372
Flammable liquids	Flam. Liq.	3	H226
Skin corrosion	Skin Corr.	1B	H314
Acute toxicity	Acute Tox.	4	H332
Serious eye damage	Eye Dam.	1	H318
Acute toxicity	Acute Tox.	4	H302
Acute toxicity	Acute Tox.	2	H330
Skin corrosion	Skin Corr.	1A	H314
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Substances or mixtures corrosive to metals	Met. Corr.	1	H290
Specific target organ toxicity - repeated exposure	STOT RE	2	H372
Substances or mixtures which in contact with water emit flammable gases	Water-react.	3	H261
Specific target organ toxicity - repeated exposure	STOT RE	2	H373
Substances or mixtures which in contact with water emit flammable gases	Water-react.	1	H260
Acute toxicity	Acute Tox.	4	H312

• Transport Information: UN 2604

Discovery and Applications

Boron trifluoride etherate, often abbreviated as BF₃·OEt₂, is a coordination complex formed from boron trifluoride (BF₃) and diethyl ether (OEt₂). This compound was developed to stabilize the highly reactive BF₃ gas, making it safer and more practical for use in laboratory and industrial settings. The discovery of boron trifluoride etherate can be traced to early 20th-century research on boron compounds and their reactivity. Boron trifluoride itself was known for its strong Lewis acid properties, but as a gas, it was challenging to handle and transport. Combining BF₃ with diethyl ether created a stable liquid that maintained BF₃’s reactivity while improving its usability, leading to widespread application in organic synthesis and catalysis.

The structure of boron trifluoride etherate consists of a central boron atom bonded to three fluorine atoms and coordinated with an ether molecule via the oxygen atom’s lone pair. This coordination is critical, as it stabilizes BF₃ while retaining its potent electron-accepting (Lewis acidic) properties. In this stabilized form, BF₃·OEt₂ is a colorless liquid, soluble in many organic solvents, and easier to store than BF₃ gas.

Boron trifluoride etherate is widely used as a catalyst in organic synthesis, particularly in reactions that require strong Lewis acids. It is commonly applied in Friedel-Crafts reactions, where it facilitates the formation of carbon-carbon bonds in the synthesis of aromatic compounds. The compound is also a valuable catalyst in alkylation, acylation, and polymerization reactions, where it activates electrophiles, enhancing the reactivity of organic substrates. In addition, boron trifluoride etherate plays a role in the production of synthetic resins and plastics, where it catalyzes polymerization reactions to form durable materials.

The utility of boron trifluoride etherate also extends to analytical chemistry, where it is used in derivatization reactions. In gas chromatography, for instance, it helps convert polar or high-boiling-point substances into volatile derivatives that can be more easily analyzed. This application is critical in the pharmaceutical and environmental sectors, where BF₃·OEt₂ assists in the accurate analysis of complex compounds.

The discovery and development of boron trifluoride etherate have provided chemists with a powerful tool for catalysis and synthesis, improving the efficiency and safety of processes involving BF₃. Its applications across organic synthesis, materials science, and analytical chemistry underscore the compound’s importance in both industrial and research environments.

References

2024. Fluorination of heterocyclic compounds accompanied by molecular rearrangements. Chemistry of Heterocyclic Compounds.
DOI: 10.1007/s10593-024-03340-0

2016. Advances in the synthesis of α-quaternary α-ethynyl α-amino acids. Amino Acids.
DOI: 10.1007/s00726-016-2276-2

2009. Stereoselective One-Pot, Three-Component Synthesis of 4-Aryltetrahydropyran via Prins-Friedel-Crafts Reaction. The Journal of Organic Chemistry.
DOI: 10.1021/jo802531h