Alpha hydroxycarboxylic acid

Structural formulae of α-, β- and γ-hydroxy acids

Alpha hydroxy carboxylic acids, or α-hydroxy carboxylic acids (AHAs), are a group of carboxylic acids featuring a hydroxy group located one carbon atom away from the acid group. This structural aspect distinguishes them from beta hydroxy acids, where the functional groups are separated by two carbon atoms.[1] Notable AHAs include glycolic acid, lactic acid, mandelic acid, and citric acid.

α-Hydroxy acids are stronger acids compared to their non-alpha hydroxy counterparts, a property enhanced by internal hydrogen bonding.[2][3][4] AHAs serve a dual purpose; industrially, they are utilized as additives in animal feed and as precursors for polymer synthesis.[5][6][7][8] In cosmetics, they are commonly used for their ability to chemically exfoliate the skin.[9]

  1. ^ Miltenberger, Karlheinz (2000). "Hydroxycarboxylic Acids, Aliphatic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a13_507. ISBN 3527306730.
  2. ^ Dawson RM, et al. (1959). Data for Biochemical Research. Oxford: Clarendon Press.
  3. ^ Handbook of Chemistry and Physics, CRC Press, 58th edition, page D147 (1977)
  4. ^ The strength of the hydrogen bonding is refelected also in the Proton nuclear magnetic resonance-spectrum of these compounds: instead of giving rise to a contribution to the broad signal of rapidly exchanged protons (between COOH, OH, NH, etc) in 2-phenyl-2-hydroxyacetic acid (mandelic acid) the proton on the alpha carbon and the proton trapped in the internal hydrogen bridge show a nice pair of doublets instead a singlet (H on alpha-C) and the formentioned broad signal of exchangable protons. So on the NMR-time scale the exchange equilibrium for the alpha-hydroxy group is frozen.
  5. ^ Casalini, Tommaso; Rossi, Filippo; Castrovinci, Andrea; Perale, Giuseppe (2019). "A Perspective on Polylactic Acid-Based Polymers Use for Nanoparticles Synthesis and Applications". Frontiers in Bioengineering and Biotechnology. 7: 259. doi:10.3389/fbioe.2019.00259. ISSN 2296-4185. PMC 6797553. PMID 31681741.
  6. ^ Storti, G.; Lattuada, M. (2017-01-01). Perale, Giuseppe; Hilborn, Jöns (eds.). "8 - Synthesis of bioresorbable polymers for medical applications". Bioresorbable Polymers for Biomedical Applications. Woodhead Publishing: 153–179. doi:10.1016/b978-0-08-100262-9.00008-2. ISBN 978-0-08-100262-9. Retrieved 2023-04-01.
  7. ^ Samantaray, Paresh Kumar; Little, Alastair; Haddleton, David M.; McNally, Tony; Tan, Bowen; Sun, Zhaoyang; Huang, Weijie; Ji, Yang; Wan, Chaoying (2020). "Poly(glycolic acid) (PGA): a versatile building block expanding high performance and sustainable bioplastic applications". Green Chemistry. 22 (13): 4055–4081. doi:10.1039/D0GC01394C. ISSN 1463-9262. S2CID 219749282.
  8. ^ Herold, B. C.; Scordi-Bello, I.; Cheshenko, N.; Marcellino, D.; Dzuzelewski, M.; Francois, F.; Morin, R.; Casullo, V. Mas; Anderson, R. A.; Chany, C.; Waller, D. P.; Zaneveld, L. J. D.; Klotman, M. E. (2002-11-15). "Mandelic Acid Condensation Polymer: Novel Candidate Microbicide for Prevention of Human Immunodeficiency Virus and Herpes Simplex Virus Entry". Journal of Virology. 76 (22): 11236–11244. doi:10.1128/JVI.76.22.11236-11244.2002. ISSN 0022-538X. PMC 136750. PMID 12388683.
  9. ^ Nutrition, Center for Food Safety and Applied (2022-11-22). "Alpha Hydroxy Acids". FDA.