Mesoxalic acid

Mesoxalic acid, also called oxomalonic acid or ketomalonic acid, is an organic compound with formula C₃H₂O₅ or HO-(C=O)₃-OH.

Mesoxalic acid is both a dicarboxylic acid and a ketonic acid. It readily loses two protons to yield the divalent anion C₃O₅, called mesoxalate, oxomalonate, or ketomalonate. These terms are also used for salts containing this anion, such as sodium mesoxalate, Na₂C₃O₅); and for esters containing the -C₃O₅- or -O-(C=O)₃-O- moiety, such as diethyl mesoxalate, C₂H₅)₂C₃O₅. Mesoxalate is one of the oxocarbon anions, which (like carbonate CO₃ and oxalate C₂O₄) consist solely of carbon and oxygen.