Alpha hydroxycarboxylic acid
Alpha hydroxy carboxylic acids, or α-hydroxy carboxylic acids (AHAs), are a group of
α-Hydroxy acids are
Uses
The synthesis and utilization of
Furthermore,
2-Hydroxy-4-(methylthio)butyric acid, alpha hydroxy carboxylic acid, is used commercially in a racemic mixture to substitute for methionine in animal feed.[11]
Synthesis and reactions
α-Hydroxy acids, such as glycolic acid, lactic acid, citric acid, and mandelic acid, serve as precursors in
One common synthesis route involves the
- R−CH(Cl)CO2H + H2O → R−CH(OH)CO2H + HCl
Another synthetic pathway for α-hydroxy acids involves the addition of
- R−CHO + HCN → R−CH(OH)CN
- R−CH(OH)CN + 2H2O → R−CH(OH)CO2H + NH3
Furthermore, specialized synthetic routes include the reaction of dilithiated carboxylic acids with oxygen, followed by aqueous workup.[18]
- R−CHLiCO2Li + O2 → R−CH(O2Li)CO2Li
- R−CH(O2Li)CO2Li + H+ → R−CH(OH)CO2H + 2Li+ + ...
Additionally, α-keto aldehydes can be transformed into α-hydroxy acids through the Cannizzaro reaction.[19]
- R−C(O)CHO + 2OH− → R−CH(OH)CO−2 + H2O
Occurrence
2-Hydroxy-4-(methylthio)butyric acid is an intermediate in the biosynthesis of 3-dimethylsulfoniopropionate, precursor to natural dimethyl sulfide.[20]
Safety
Alpha hydroxy acids are generally safe when used on the skin as a cosmetic agent using the recommended dosage. The most common side-effects are mild skin irritations, redness and flaking.[9] The United States Food and Drug Administration (FDA) and Cosmetic Ingredient Review expert panels both suggest that alpha hydroxy acids are safe to use as long as they are sold at low concentrations, pH levels greater than 3.5, and include thorough safety instructions.[9]
The FDA has warned consumers that care should be taken when using alpha hydroxy acids after an industry-sponsored study found that they can increase the likelihood of sunburns.[9] This effect is reversible after stopping the use of alpha hydroxy acids. Other sources suggest that glycolic acid, in particular, may protect from sun damage.[9]
See also
- Beta hydroxy acid
- Hydroxybutyric acid
- Omega hydroxy acid
Further reading
- Atzori L, Brundu MA, Orru A, Biggio P (March 1999). "Glycolic acid peeling in the treatment of acne". Journal of the European Academy of Dermatology and Venereology. 12 (2): 119–22. S2CID 9721678.
- "Alpha Hydroxy Acids for Skin Care". Cosmetic Dermatology, Supplement: 1–6. October 1994.
- Kalla G, Garg A, Kachhawa D (2001). "Chemical peeling--glycolic acid versus trichloroacetic acid in melasma". Indian Journal of Dermatology, Venereology and Leprology. 67 (2): 82–4. PMID 17664715.
- Kempers S, Katz HI, Wildnauer R, Green B (June 1998). "An evaluation of the effect of an alpha hydroxy acid-blend skin cream in the cosmetic improvement of symptoms of moderate to severe xerosis, epidermolytic hyperkeratosis, and ichthyosis". Cutis. 61 (6): 347–50. PMID 9640557.
References
- ISBN 978-3527306732.
- ^ Dawson RM, et al. (1959). Data for Biochemical Research. Oxford: Clarendon Press.
- ^ Handbook of Chemistry and Physics, CRC Press, 58th edition, page D147 (1977)
- ^ 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 rappidly 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.
- ^ PMID 31681741.
- ^ ISBN 978-0-08-100262-9. Retrieved 2023-04-01.
- ^ S2CID 219749282.
- ^ PMID 12388683.
- ^ a b c d e Nutrition, Center for Food Safety and Applied (2022-11-22). "Alpha Hydroxy Acids". FDA.
- PMID 17825297.
- PMID 12079051.
- ^ ISBN 978-3527306732.
- ISBN 978-3527306732.
- doi:10.1246/bcsj.9.8.
- .
- OCLC 27813843.
- OCLC 1007924903.)
{{cite book}}
: CS1 maint: location missing publisher (link - ISBN 978-0-471-72091-1
- ISBN 978-0-471-72091-1
- S2CID 21460292.