Sodium diacetate

Preparation and structure

The salt forms upon half-neutralization of acetic acid followed by evaporation of the solution. It can be viewed as the result of homoassociation, an effect that enhances the acidity of acetic acid in concentrated solution:

2 CH₃CO₂H + NaOH → Na⁺[(CH₃CO₂)₂H]⁻ + H₂O

Also described as the sodium acid salt of acetic acid, it is best described as the sodium salt of the hydrogen-bonded anion (CH₃CO₂)₂H⁻. The O···O distance is about 2.47 angstrom. The species has no significant existence in solution but forms stable crystals.