Boron trifluoride etherate

It is a colorless liquid, although older samples can appear brown.

The compound is used as a source of boron trifluoride in many chemical reactions that require a Lewis acid.

[1] The compound features tetrahedral boron coordinated to a diethylether ligand.

[2] Many analogues are known, including the methanol complex.

Boron trifluoride etherate serves as a source of boron trifluoride according to the equilibrium: The BF3 binds to even weak Lewis bases, inducing reactions of the resulting adducts with nucleophiles.

Bond Line Structure of Boron Trifluoride Etherate
NFPA 704 four-colored diamond Health 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gas Flammability 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuel Instability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorus Special hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid