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Introduction
Monochloroacetic acid (MCA) is a halogenated acetic acid derivative widely used as an intermediate in the production of a variety of organic compounds. It is one of the most important building block chemicals in the global chemical industry.
CAS Number: 79-11-8
Synonyms:,Chloroacetic acid,Acetic acid, chloro-,MCA,MCAA
Chloromethanecarboxylic acid,2-Chloroethanoic acid
Discovered in the mid-19th century, MCA has become a critical intermediate in agrochemicals, surfactants, dyes, pharmaceuticals, and specialty chemicals.
Its reactivity stems from the presence of both the carboxyl group and the electron-withdrawing chlorine atom, making it highly versatile for nucleophilic substitution reactions.
Chemical and Physical Properties
Molecular Formula: C₂H₃ClO₂
Molecular Weight: 94.50 g/mol
IUPAC Name: 2-chloroacetic acid
Structure:
Functional groups: carboxyl (-COOH), chloro (-Cl)
The chlorine substituent increases the electrophilic character of the α-carbon.
Physical Characteristics:
Appearance: White crystalline solid or colorless crystals
Melting point: 61 – 63 °C
Boiling point: 189 – 190 °C (with decomposition)
Density: 1.58 g/cm³ at 20 °C
Solubility: Soluble in water, ethanol, methanol, acetone, and other polar solvents
pKa: 2.85 (stronger acid than acetic acid due to inductive effect of chlorine)
Odor: Slightly pungent, vinegar-like
Reactivity Profile:
Strongly corrosive, reacts violently with bases, amines, and alcohols
Undergoes nucleophilic substitution at the α-carbon
Susceptible to hydrolysis and polymerization under extreme conditions
Methods of Production
Industrial Routes
Monochloroacetic acid is primarily produced by chlorination of acetic acid or hydrolysis of trichloroethylene.
(a) Chlorination of Acetic Acid:
CH₃COOH + Cl₂ → ClCH₂COOH + HCl
Catalyst: Red phosphorus or sulfur-based catalysts
By-products: Dichloroacetic acid, trichloroacetic acid
(b) Hydrolysis of Trichloroethylene:
CCl₂=CHCl + 2 H₂O → ClCH₂COOH + 2 HCl
Conducted under controlled temperature and pressure
Laboratory Synthesis
In smaller scales, MCA can be synthesized through chlorination of acetic anhydride or acetyl chloride, but these methods are less efficient compared to industrial processes.
Purification
MCA is purified through crystallization and distillation, ensuring removal of dichloroacetic and trichloroacetic acid contaminants.
Applications
Monochloroacetic acid is a crucial intermediate with extensive industrial applications:
Agrochemicals
Used in the synthesis of herbicides (2,4-D, MCPA)
Precursor to thioglycolic acid for fungicides and pesticides
Intermediate in the production of glyphosate
Carboxymethyl Cellulose (CMC)
MCA reacts with cellulose in alkaline conditions to produce CMC, a widely used thickener, stabilizer, and binder in food, pharmaceuticals, and cosmetics.
Surfactants
Production of amphoteric surfactants like betaines
Key in mild surfactants for shampoos, detergents, and personal care products
Pharmaceuticals
Used in the synthesis of vitamins, anesthetics, analgesics
Precursor for ibuprofen intermediates
Component in certain sulfa drugs
Dyes and Pigments
MCA derivatives are employed in indigo dyes, reactive dyes, and textile auxiliaries
Other Applications
Production of thioglycolic acid (used in PVC stabilizers, hair perms)
Intermediate for glycine and other amino acids
Used in adhesives, coatings, and specialty polymers
Mechanism of Reactions
MCA undergoes nucleophilic substitution reactions at the α-carbon due to the electron-withdrawing chlorine atom.
Hydroxide ions replace chlorine → glycolic acid
Amines replace chlorine → glycine derivatives
Thiols replace chlorine → thioglycolic acid
This versatility makes it a “platform chemical” in industrial synthesis.
SAFETY INFORMATION ABOUT MONO CHLORO ACETIC ACID
First aid measures:
Description of first aid measures:
General advice:
Consult a physician.
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
If inhaled:
If breathed in, move person into fresh air.
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately.
Wash off with soap and plenty of water.
Consult a physician.
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
If swallowed:
Do NOT induce vomiting.
Never give anything by mouth to an unconscious person.
Rinse mouth with water.
Consult a physician.
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment.
Avoid breathing vapours, mist or gas.
Evacuate personnel to safe areas.
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste.
Keep in suitable, closed containers for disposal.
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place.
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles.
Faceshield (8-inch minimum).
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
Skin protection:
Handle with gloves.
Gloves must be inspected prior to use.
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product.
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices.
Wash and dry hands.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls.
If the respirator is the sole means of protection, use a full-face supplied air respirator.
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions.
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company.
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product
