Glycolic acid

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Glycolic acid
Chemical structure of glycolic acid
Ball-and-stick model of glycolic acid
IUPAC name 2-Hydroxyethanoic acid
Other names glycolic acid,
hydroxyacetic acid
Identifiers
CAS number [79-14-1]
RTECS number MC5250000
SMILES O=C(O)CO
Properties
Molecular formula C2H4O3
Molar mass 76.05 g/mol
Appearance colorless solid
Density 1.27 g/cm3
Melting point

75 °C
Boiling point

decomposes
Solubility in water 0.1 g/mL
Solubility in other solvents alcohols, acetone,
acetic acid and
ethyl acetate[1]
Acidity (pKa) 3.83
Hazards
Main hazards Corrosive (C)
NFPA 704
1
3
0
 
R-phrases R22-R34
S-phrases S26-S36/37/39-S45
Flash point 129 °C[2]
Related compounds
Related α-hydroxy acids lactic acid
Related compounds acetic acid,
glycerol
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Glycolic acid (or hydroxyacetic acid) is the smallest α-hydroxy acid (AHA). It appears in the form of a colorless, odorless and hygroscopic crystalline solid that is highly soluble in water and related solvents. Glycolic acid is associated with sugar-crops and is isolated from sugarcane, sugar beets, pineapple, canteloupe, and unripe grapes.

Contents

[edit] Uses

Due to its excellent capability to penetrate skin, glycolic acid finds applications in skin care products, most often as a chemical peel performed by a dermatologist in concentrations of 20%-80% or at-home kits in lower concentrations of 10%. It is used to improve the skin's appearance and texture. It may reduce wrinkles, acne scarring, hyperpigmentation and improve many other skin conditions. Once applied, glycolic acid reacts with the upper layer of the epidermis, weakening the binding properties of the lipids that hold the dead skin cells together. This allows the outer skin to "dissolve" revealing the underlying skin.

Glycolic acid is also a useful intermediate for organic synthesis, in a range of reactions including: oxidation-reduction, esterification and long chain polymerization. It is used as a monomer in the preparation of polyglycolic acid and other biocompatible copolymers (e.g. PLGA). Among other uses this compound finds employment in the textile industry as a dyeing and tanning agent, in food processing as a flavoring agent and as a preservative. Glycolic acid is often included into emulsion polymers, solvents and additives for ink and paint in order to improve flow properties and impart gloss.

[edit] Preparation

Glycolic acid is isolated from natural sources and is inexpensively available. It can be prepared by the reaction of chloroacetic acid with sodium hydroxide followed by re-acidification.

Glycolic acid can also be prepared using an enzymatic biochemical process which produces fewer impurities compared to traditional chemical synthesis, requires less energy in production and produces less co-product.[3] This process is used by the specialty chemical company CrossChem.

[edit] Safety

Glycolic acid is a strong irritant.[4] Like ethylene glycol, it is metabolized to oxalic acid, which makes it dangerous if ingested.

[edit] References

  1. ^ DuPont Glycolic Acid Technical Information. Retrieved on 2006-07-06.
  2. ^ Glycolic Acid MSDS. University of Akron. Retrieved on 2006-09-18.
  3. ^ GlyAcid EBP Crystalline at CrossChem.net
  4. ^ Glycolic Acid MSDS. ICSC:NENG1537 International Chemical Safety Cards (WHO/IPCS/ILO). Retrieved on 2006-06-08.

[edit] External links

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