Oxalate

The structure of the oxalate anion

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

An oxalate (also ethanedioate) is a salt or ester of oxalic acid. As a salt, the oxalate anion has the chemical formula C₂O₄²⁻ or (COO)₂²⁻.

Consumption of oxalates (for example, the grazing of animals on oxalate-containing plants such as greasewood), or human consumption of Sorrel may result in kidney disease or even death due to oxalate poisoning.

The charge on oxalate allows it to act as a chelator of various positively charged metal ions.

Much of its other properties resemble oxalic acid.

Examples

• sodium oxalate - Na₂C₂O₄
• calcium oxalate - CaC₂O₄, a major component of kidney stones
• dimethyl oxalate - (CH₃)₂C₂O₄
• phenyl oxalate ester - (C₆H₅)₂C₂O₄
• potassium ferrioxalate - [K₃[Fe(C₂O₄)₃], an iron complex with oxalate ligands
• ammonium oxalate - (NH₄)₂C₂O₄