Hydroxyacetate

Hydroxyacetate is the anion derived from hydroxyacetic acid, also known as glycolic acid, by deprotonation of the carboxyl group. It is commonly referred to as glycolate and exists in solution as the monovalent anion HO-CH2-COO−. In chemical reactions, it can form various salts, such as sodium glycolate.

Chemistry and properties: The hydroxyacetate anion has the formula C2H3O3−. In aqueous solution, glycolic acid and hydroxyacetate are in acid–base equilibrium, with pKa of glycolic acid around 3.83, so the balance between the neutral acid and the conjugate base shifts with pH. The species can participate in coordination to metals and appear in ester or salt forms depending on the reaction conditions.

Occurrence and applications: In biology, glycolate is an intermediate in pathways such as the glyoxylate cycle and plant photorespiration. Industrially, glycolates and glycolic acid salts are used in cosmetics as exfoliants and humectants, and they serve as chelating agents in detergents and cleaners. In organic synthesis, hydroxyacetate residues can be found in esters and certain coordination compounds.

Safety: Glycolic acid and its salts are generally less irritating than the acid itself, but concentrated preparations can be corrosive or irritating to skin, eyes, and mucous membranes. Proper handling and protective equipment are advised.

See also: glycolic acid, glycolate.