Methoxyacetic acid

Methoxyacetic acid
Names
IUPAC name
2-Methoxyacetic acid
Other names
2-Methoxyacetic acid
Methyl glycolic acid
Identifiers
ChEBI
ChemSpider
ECHA InfoCard 100.009.904 Edit this at Wikidata
EC Number
  • 210-894-6
UNII
Properties
C3H6O3
Molar mass 90.08 g/mol−1
Appearance Clear, colorless, viscous liquid with a pungent odor
Density 1.1768 g/cm−3
Melting point 7–9 °C (45–48 °F; 280–282 K)
Boiling point 202–204 °C (396–399 °F; 475–477 K)
Soluble in water, ethanol, and diethyl ether
Vapor pressure 1.8 mbar (20 °C)
4.8 mbar (50 °C)
Acidity (pKa) 3.57
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Methoxyacetic acid is the organic compound with the formula CH3OCH2CO2H. 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.

Production

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.

Properties

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]

Applications

Methoxyacetic acid is a precursor to two commercial fungicides, oxadixyl and mefenoxam.

Former applications

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.

Safety

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]

References

  1. ^ Teles, J. Henrique; Hermans, Ive; Franz, Gerhard; Sheldon, Roger A. (2015). "Oxidation". Ullmann's Encyclopedia of Industrial Chemistry. pp. 1–103. doi:10.1002/14356007.a18_261.pub2. ISBN 978-3-527-30385-4.
  2. ^ Mebus, C.A.; Welsch, F. (1989). "The possible role of one-carbon moieties in 2-methoxyethanol and 2-methoxyacetic acid-induced developmental toxicity". Toxicology and Applied Pharmacology. 99 (1): 98–109. doi:10.1016/0041-008X(89)90115-4. PMID 2471293.
  3. ^ King, Edward J. (1960). "The Thermodynamics of Ionization of Amino Acids. V. The Ionization Constants of 3-Methoxy-DL-alanine (O-Methylserine) and Methoxyacetic Acid 1". Journal of the American Chemical Society. 82 (14): 3575–3578. doi:10.1021/ja01499a025. ISSN 0002-7863.
  4. ^ "Espacenet – search results". worldwide.espacenet.com. Retrieved 2023-12-05.
  5. ^ "Substance Information - ECHA". echa.europa.eu. Retrieved 2023-12-05.
  6. ^ Parajuli, Keshab R.; Zhang, Qiuyang; Liu, Sen; Patel, Neil K.; Lu, Hua; Zeng, Shelya X.; Wang, Guangdi; Zhang, Changde; You, Zongbing (2014). "Methoxyacetic acid suppresses prostate cancer cell growth by inducing growth arrest and apoptosis". American Journal of Clinical and Experimental Urology. 2 (4): 300–312. ISSN 2330-1910. PMC 4297326. PMID 25606576.