Glycolic acid

Hydroxyacetic

Colorless and odorless crystals

Fixed

1.26 g · cm -3

80 ° C.

100 ° C ( decomposition)

27.5 hPa ( 25 ° C)

3.83

Very good in water ( 1000 g · l-1 at 25 ° C), acetone, ethanol and diethyl ether

Risk

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Glycolic acid ( hydroxyacetic acid ) is the simplest α -hydroxycarboxylic acid having the formula HOCH 2 -COOH. The hydroxymethyl group can be oxidized as in other primary alcohols via aldehyde ( glyoxylic acid ) to the carboxyl group ( oxalic acid).

Occurrence

Glycolic acid found in unripe grapes, in sugar cane juice, in sugar beet, in the leaves of wild grape and rosemary. As the oxidation product is also included in glacial acetic acid. Due to their natural glycolic acid which is counted to the fruit acids.

Production

Industrially, glycolic acid is synthesized by alkaline hydrolysis of chloroacetic acid:

The synthesis of carbon monoxide, water and formaldehyde is possible:

Use

Glycolic acid is used as a 20 % aqueous solution to remove rust from pipes by chelation of calcium and iron ions. In the textile industry, the acid for preservation ( " Avivierung " ) and as a catalyst in the leather industry for descaling of animal skins, used to chrome tanning and dyeing. In the synthesis of ( as a mild organic acid ) as well as starting material for various esters is glycolic use.

In addition, the fruit acid glycolic acid is used for skin care. Here they met a scrub function, thus improving skin appearance.

Safety

The combustible glycolic acid acts in pure form corrosive to eyes, skin, mucous membranes and respiratory tract. In animal experiments with rats, guinea pigs and cats they proved to be of low toxicity ( LD50 oral / rat 1.950 g / kg, 1.92 g / kg orally / guinea pig). They showed effects on the sense of smell, breathing disorders, sleepiness and changes in stomach and kidney tissue.