Preparation
It is prepared by the reaction of chloroacetic acid with sodium hydroxide followed by re-acidification. The net reaction can be summarized as follows:
- ClCH2CO2H + NaOH → HOCH2CO2H + NaCl
In this way, a few million kilograms are produced annually. Catalyzed reaction of formaldehyde with synthesis gas (carbonylation of formaldehyde) is a particularly economical preparative route. Other methods, not apparently in use, include hydrogenation of oxalic acid with nascent hydrogen and the hydrolysis of the cyanohydrin derived from formaldehyde. Some of today's glycolic acids are formaldehyde and formic acid free. Glycolic acid can be isolated from natural sources, such as sugarcane, sugar beets, pineapple, cantaloupe, and unripe grapes.
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. Each route can be evaluated for its relative costs and benefits.
Read more about this topic: Glycolic Acid
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