Molecule of the Month April 2019

written at 30.04.2019
Pure Monochloroacetic Acid

Molecule of the Month


Date:               April 2019

Subject:          Pure Monochloroacetic Acid

Chloracetic acid, commonly known as monochloroacetic acid or MCA, is a useful building block in organic systhesis. End products include drugs, dyes and pesticides. It’s largest-scale application is in the preparation of carboxymethyl cellulose, a thickening agent. Two other, perhaps more well know end-products, are glyphosate and epinephrine (adrenaline).

The main industrial route to MCA is the chlorination of acetic acid using acetic anhydride (AA) as a catalyst. Some dichloroacetic acid (DCA) is formed. As many applications required low DCA content, typically < 0.1%, the “crude” MCA needs to be purified. Fractional crystallization can be used to obtain almost pure MCA. The residue stream, after recovering the AA, still contains a useful amount of MCA. But as DCA is about 1/3rd the content and their melting points are quite close, separation by distillation is very difficult. This problem can be solved by catalytic hydrogenation of the DCA back to MCA.

Buss ChemTech has developed two routes for this: (1) hydrogenation of the crude MCA/DCA mix with subsequent crystallization and then distillation of the AA, or (2) hydrogenation of the residue stream from crystallization and recycling the product back to the crystallization section. Both routes result in pure MCA stream with < 0.05% DCA.




To learn more about the two routes, contact Thomas Blocher, Business Manager Reaction Technology at +41 61 825 6317 or by liam-e

External Input/sources for this Article: MCA Flyer, Wikipedia Article Chloroacetic Acid