What Is Trichloroethylene CAS 79-01-6?
Trichloroethylene, commonly abbreviated as TCE, is a non-flammable, colorless chlorinated hydrocarbon with a mildly sweet, chloroform-like odor. Its CAS registry number is 79-01-6 and its chemical formula is C2HCl3. TCE belongs to the halocarbon group of solvents and is known for rapid evaporation, high density and strong dissolving power. For nearly a century, its ability to dissolve oils, greases, waxes, tars and resins has made it one of the most valuable solvents in heavy industry.
Other names for the compound include ethylene trichloride, 1,1,2-trichloroethylene and triclene. The combination of chemical stability, non-flammability and a moderate evaporation rate made it a safer alternative to the highly volatile solvents used in earlier industrial processes.
Key Chemical Properties of Trichloroethylene
Trichloroethylene has a molar mass of 131.39 g/mol and appears as a colorless liquid at room temperature. It boils at 87.2 degrees Celsius, equivalent to 189.0 degrees Fahrenheit, and has a density of about 1.46 g/cm3. Because the liquid is heavier than water and the vapor is heavier than air, careful ventilation and handling practices are required in the workplace.
The solvency power of TCE is excellent for oils, greases, fats, waxes and resins, which is why it performs so well in cleaning and extraction duties. Its high stability also allows the solvent to be reused in vapor degreasing equipment without rapid degradation, which improves process economy.
Metal Degreasing and Precision Cleaning
Metal processing is the largest application area for trichloroethylene. The solvent is widely used to remove stubborn grease, oil stains, cutting fluids and contaminants from metal equipment, machine parts and precision components. Because TCE is non-flammable and has a comparatively high boiling point, it supports steam degreasing operations that require thorough cleaning at elevated temperatures without fire risk.
Components cleaned with TCE typically emerge free of residue after evaporation, which is critical for downstream coating, plating or assembly steps in automotive, aerospace and general manufacturing. The consistent cleaning result also reduces reject rates and extends the service life of tooling.
Refrigerant Synthesis and Other Process Applications
Trichloroethylene is an essential chemical raw material in the production of hydrofluorocarbon refrigerants. It participates in synthesis routes that lead to refrigerants used in HVAC systems, refrigeration equipment and related industrial cooling applications. This application connects the TCE market to the broader air-conditioning and cold-chain industries, which depend on reliable supplies of high-purity feedstock.
In textile processing, TCE serves as a specialized extraction solvent that removes natural impurities such as waxes and oils from cotton and wool fibers before dyeing and finishing. In the pharmaceutical industry, it acts as a chemical intermediate that participates in synthesis reactions for the preparation of active ingredients and pharmaceutical compounds.
Beyond industrial uses, trichloroethylene appears as a functional ingredient in a number of everyday and chemical products. Historical and current examples include typewriter correction fluid, adhesives and lubricants, fabric stain removers, paint removers and thinners, and carpet cleaning formulations.
Safety, Health and Regulatory Considerations
Although highly effective, TCE must be handled with care. Long-term exposure carries potential health risks, and improper disposal can lead to environmental contamination, particularly of groundwater. Regulatory attention has increased worldwide as a result of these concerns.
Under the European Union REACH regulation, trichloroethylene is subject to restriction, and its usage is controlled in the United States and other regions. Many industries are gradually evaluating safer alternatives while still relying on TCE where its unique performance cannot be easily replaced. Employers should provide adequate ventilation, appropriate personal protective equipment and continuous exposure monitoring wherever TCE is used.
Frequently Asked Questions
Is trichloroethylene flammable? No, TCE is non-flammable under normal conditions, which is one reason it is preferred for vapor degreasing and cleaning applications where fire safety matters, but it can decompose at high temperatures to form hazardous by-products.
What is the CAS number of trichloroethylene? The CAS registry number of trichloroethylene is 79-01-6, and its chemical formula is C2HCl3 with a molar mass of 131.39 g/mol.
What is TCE mainly used for? TCE is mainly used for metal degreasing and precision cleaning, as a raw material for refrigerant production, as an extraction solvent in textile processing, and as a chemical intermediate in pharmaceutical production.
What is the boiling point of trichloroethylene? Trichloroethylene boils at 87.2 degrees Celsius, or 189.0 degrees Fahrenheit, at standard pressure.
What are the main health risks of TCE exposure? Long-term exposure carries significant health risks, and the solvent can contaminate groundwater if disposed of improperly, so employers should provide adequate ventilation, personal protective equipment and continuous exposure monitoring wherever TCE is used.
Is TCE still allowed in Europe? Trichloroethylene is restricted under EU REACH and controlled in the United States and other regions, so users must verify current authorisation and workplace exposure limits before application.