Monochloroacetic

Monochloroacetic acid, also known as chloroacetic acid, is an organochlorine carboxylic acid in which one hydrogen of acetic acid is replaced by chlorine. Its chemical formula is C2H3ClO2 and its molar mass is about 94.5 g/mol. It is a colorless, highly hygroscopic crystalline solid that decomposes on strong heating. It is miscible with water and with many organic solvents. The carboxyl group has a pKa around 2.8, reflecting its relatively strong acidity for a simple aliphatic carboxylic acid.

Industrial production of monochloroacetic acid typically proceeds by chlorination of acetic acid with chlorine, often in the presence of catalysts. The reaction mixture yields monochloro-, dichloro-, and trichloroacetic acids, which are separated and purified to obtain the monochloro compound. In some processes, chlorination of precursors such as chloroacetyl chloride followed by hydrolysis is used. The product is usually purified by crystallization or distillation under controlled conditions.

Uses and applications of monochloroacetic acid include its role as a versatile chemical intermediate. It is used to prepare various derivatives through nucleophilic substitution at the chloromethyl carbon, such as sodium chloroacetate and related compounds. A major downstream application is the production of carboxymethyl cellulose (CMC), where monochloroacetic acid is employed under alkaline conditions to introduce carboxymethyl groups into cellulose. It also serves as a building block in the synthesis of herbicides, pharmaceuticals, detergents, and specialty polymers.

Safety and handling: monochloroacetic acid is highly corrosive and toxic by inhalation, ingestion, or dermal exposure. It can cause severe burns and irritate the eyes and respiratory tract. It should be stored in corrosion-resistant containers and handled with appropriate PPE, away from bases and incompatible materials. Environmental release should be minimized due to toxicity to aquatic life.