June 15, 2024

Monochloroacetic acid: A versatile yet hazardous chemical

Monochloroacetic acid (MCA) is an organic compound with the chemical formula ClCH2CO2H. It is a colorless, crystalline solid that finds important industrial applications but also poses health hazards if not handled properly. In this article, we will explore the uses, production, handling and risks of monochloroacetic acid.

Uses of Monochloroacetic acid

MCA finds numerous applications due to its reactive chloromethyl group which allows it to undergo substitutions and additions easily. Some major uses of MCA are:

Herbicide Production
Monochloroacetic acid serves as a building block in the manufacture of many phenoxy herbicides like 2,4-D. The chloromethyl group of MCA reacts with phenol derivatives to form these widely used herbicides. MCA herbicides are effective in controlling broad-leaf weeds in grasses and cereal crops.

Thioglycolic Acid Production
MCA is reacted with hydrogen sulfide or sodium hydrogen sulfide to produce thioglycolic acid. Thioglycolic acid and its salts find applications as depilatories in hair removal creams and products. They break the disulfide bonds in hair keratin, making the hairs and dead.

Production of Cyclohexanone and Cyclohexanol
MCA allows the manufacture of cyclohexanone and cyclohexanol, important industrial chemicals, through a multistage reaction involving phosgene and further processing. Cyclohexanone is used to synthesize nylon while cyclohexanol is converted to adipic acid, another important nylon intermediate.

MCA also serves as a building block in the synthesis of various medicines, polymers and dyestuffs. It is used in the manufacture of pharmaceuticals like vitamins B1 and B12. It has applications as a slimicide in the paper industry and as an intermediate in some pesticide production processes.

Production of Monochloroacetic Acid
MCA is produced commercially using two different processes involving either chlorination of acetate or oxidation of chloroacetate salts.

The more common chlorination process involves reacting chlorine with sodium acetate in the presence of a catalyst like aluminum chloride or ferric chloride. Sodium Monochloroacetate formed is hydrolyzed using sulfuric acid to give monochloroacetic acid as the end product.

In the oxidative process, chloroacetate salts like potassium chloroacetate are reacted with an oxidizing agent like bromine or sodium hypochlorite to yield monochloroacetic acid and byproducts. This process is less adopted on an industrial scale.

Handling and Risks of MCA

Being a chlorinated acid, monochloroacetic acid is highly corrosive in nature and can cause severe burns on contact with skin or eyes. It is also toxic if ingested or inhaled. Some important safety precautions while handling MCA are:

– Workers should wear gloves, safety goggles and protective clothing to avoid contact with skin or eyes. Leak-proof goggles are recommended.

– Monochloroacetic acid solutions should be stored in corrosion-resistant containers preferably made of polyethylene, polypropylene or stainless steel.

– Drying and evaporation of MCA solutions should be done with localized ventilation as the vapors can cause respiratory irritation.

– In case of spills, absorbent materials like soda ash, sand or vermiculite should be used to soak up the spill followed by sweeping and disposal as chemical waste.

– Exposure to high doses may cause internal bleeding, kidney and liver damage due to acidity and formation of methylene cross-links in proteins. It is rated as a possible human carcinogen.

– Adequate first aid involving irrigation of exposed body parts with water and seeking medical care is critical in case of exposure.

– Legislation exists in many countries to control occupational exposure to monochloroacetic acid and regulate its manufacture and use.

While monochloroacetic acid serves as an important building block in industry for manufacturing herbicides, pharmaceuticals and other chemicals, it comes with occupational hazards due to its high acidity and potential toxicity. With proper care, training of workers and use of safety equipment, hazards from this useful but dangerous chemical can be minimized to allow its safe industrial production and applications. Regulatory authorities also play a role in standardizing safety practices.

1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it