Solvent-system definition of acids and bases

This recognizes autoionisation of some aprotic solvents, such as boron trifluoride:

Notice the similarity with autoionisation (ie. autoprotolysis) of water.

In the solvent-system definition, a solute which increases the concentration of the cation generated by autoionisation of the solvent is called an acid, and a solute which increases the concentration of the anion generated by autoionisation of the solvent is called a base.

BrF₂AsF₆, called Difluorobromine(III) hexafluoroantimonate(V), is a salt without any obvious uses. But it is soluble in BrF₃. It disassociates into BrF₂⁺ and AsF₆^-, hence we would call it an acid.

Another example is dissolving sodium amide in ammonia. The autoionisation equation of ammonia is:

Since sodium amide splits into Na⁺ and NH₂^-, we would call it a base.