Inorganic Nonaqueous Solvent - Nonaqueous Acid-base Chemistry

Nonaqueous Acid-base Chemistry

The acid-base reactions in non-aqueous solvents are typically described by means of the solvent-system definition, although the regular Brønsted-Lowry theory may be applied for the protic solvents, which possess a hydrogen atom that can dissociate. According to the solvent-system definition, acids are the compounds that increase the concentration of the solvonium (positive) ions, and bases are the compounds that result in the increase of the solvate (negative) ions, where solvonium and solvate are the ions found in the pure solvent in equilibrium with its neutral molecules:

protic solvents autodissociation

2NH₃ ⇌ NH₄+ (ammonium) + NH₂− (amide)

3HF ⇌ H₂F+ + HF₂- (hydrogen difluoride)

2H₂SO₄ ⇌ H₃SO₄+ + HSO₄-

aprotic solvents autodissociation

N₂O₄ ⇌ NO+ (nitrosonium) + NO₃− (nitrate)

2SbCl₃ ⇌ SbCl₂+ (dichloroantimonium) + SbCl₄- (tetrachloroantimonate)

POCl₃ ⇌ POCl₂+ + POCl₄-

Thus NaNH₂ is a base and NH₄Cl is an acid in liquid ammonia, and they react, producing the salt and the solvent:

NaNH₂ + NH₄Cl → 2NH₃ + NaCl

or, for an aprotic example,

NaNO₃ + NOCl → N₂O₄ + NaCl