Boron trifluoride

Boron trifluoride (BF₃, trifluoroborane) is a pungent colourless toxic gas. In moist air it forms white fumes. Boron trifluoride can be handled as a liquid in a Lewis acid-base adduct with diethyl ether. The molecule BF₃ consists of boron and fluorine in a trigonal planar geometry.

Boron is electron deficient and in chemical reactions BF₃ is a Lewis acid, for example reacting with fluorides to form tetrafluoroborate salts:

CsF + BF₃ → CsBF₄

Uses:

• applied as dopant in ion implantation
• initiates polymerisation reactions of unsaturated compounds. Example polyethers

References

Material safety datasheets:

• http://www.osha.gov/dts/chemicalsampling/data/CH_221700.html
• http://www.cdc.gov/niosh/ipcsneng/neng0231.html