Methoxyacetic acid is the organic compound with the formula . It can be viewed as a derivative of acetic acid in which a hydrogen atom of the methyl group is replaced by a methoxy group. As indicated by the synonym methyl glycolic acid, and as the simplest ether carboxylic acid, methoxyacetic acid can be understood as a methyl ether of glycolic acid.
In principle the compound can be prepared by reaction of sodium methoxide with monochloroacetic acid. The industrial route involves the oxidation of 2-methoxyethanol with air or oxygen in the presence of platinum catalysts.[1]
In both humans and animals, 2-methoxyacetic acid forms via the rapid oxidation of 2-methoxyethanol[2] by the action of alcohol dehydrogenases.
Methoxyacetic acid is a colorless, viscous, and corrosive liquid with a pungent odor which, at 7 °C, freezes to a mass similar to glacial acetic acid. Due to the low solvation energy of its methoxy group, methoxyacetic acid, with a pKa value of 3.57, is more acidic than acetic acid (pKa 4.757) and glycolic acid (pKa 3.832).[3]
Ultra-pure methoxyacetic acid (purity of 99.8%, freezing point of 8.4 °C) can be obtained via the multistep crystallization of the raw distillate, which is free of acid contaminations.[4]
Methoxyacetic acid is a precursor to two commercial fungicides, oxadixyl and mefenoxam.
Due to its reprotoxic properties, earlier consumer and industrial applications of methoxyacetic acid as a disinfectant, biocide, or as a cleaner for the decalcification of surfaces are now obsolete. The same is true for substances such as the solvent 2-methoxyethanol or the PVC plasticizer bis(2-methoxyethyl) phthalate, which are metabolized to methoxyacetic acid.
Due to its considerable reprotoxic potential, methoxyacetic acid has been adopted into the list of SVHC substances (substances of very high concern)[5] and is only registered as an intermediate product for industrial purposes under strictly controlled conditions.
In laboratory tests, methoxyacetic acid inhibits the growth of tumor cells.[6]