Boron Trifluoride and Tetrafluoroboric Acid

The manufacture of boron trifluoride proceeds either discontinuously by reacting borates with fluorspar and oleum or continuously by reacting, for example, hydrogen fluoride with boric acid in the presence of sulfuric acid, to bind the water formed  

The reaction of boric acid with fluorosulfonic acid also yields boron trifluoride  

Pure boron trifluoride is marketed as a compressed gas. It is utilized mainly in the organic industry as a Friedel-Crafts catalyst (Lewis acid) in the form of its complexes or addition compounds with, for example, ether, alcohols, carboxylic acids etc. or as a pure substance. 

Tetrafluoroboric acid is industrially important and is manufactured from boric acid and hydrogen fluoride  

Alkali, ammonium and transition metal fluoroborates can be produced from the acid. These fluoroborates are utilized as fluxes in the galvanic deposition of metals, as flame retardants etc. 

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Preparation of the reagent is simple. It involves passing a stream of fluorine (10% in nitrogen) to a mixture of DABCO-IV-oxide, boron trifluoride, and tetrafluoroboric acid at 0 . On evaporation, the solid is collected and washed with DME (75% yield). 

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