Tetrachloroethylene and perchloroethylene are the exact same chemical substance. Tetrachloroethylene is the formal IUPAC name, perchloroethylene is the traditional industrial name, and the abbreviations PERC and PCE are used interchangeably across the industry. The systematic name tetrachloroethene is also used in scientific literature. The compound is registered under the CAS number 127-18-4 with the molecular formula C2Cl4, and it is one of the most important chlorinated solvents in commercial use, particularly in dry cleaning and industrial metal degreasing.
Same Chemical, Different Names
The variety of names for this one substance can confuse buyers and new industry professionals. The following terms all refer to the same compound:
Tetrachloroethylene, the IUPAC-preferred name
Tetrachloroethene, the systematic name
Perchloroethylene, the common industrial name
Perchlorethylene, a common spelling variant
PERC and PCE, the standard abbreviations
When a supplier lists tetrachloroethylene, perchloroethylene, or PERC on a certificate of analysis or safety data sheet, the material is identical and carries the same CAS number 127-18-4.
Physical and Chemical Properties
Tetrachloroethylene is a colorless, dense, volatile liquid with a sharp, ether-like odor. Its key physical data are:
CAS number: 127-18-4
Molecular formula: C2Cl4
Molecular weight: 165.83
Melting point: approximately -22.4 degrees Celsius
Boiling point: approximately 121 degrees Celsius
Density: about 1.62 g/mL at 20 degrees Celsius
Vapor density: approximately 5.83 times that of air
Vapor pressure: about 1.9 kPa at 20 degrees Celsius
Solubility in water: very low, in the range of 0.02 g per 100 mL
The high density and very low water solubility of PERC are important for both its industrial behavior and its environmental behavior, because released solvent tends to sink through soil and groundwater rather than dissipate.
Industrial and Commercial Applications
Dry Cleaning
PERC is the most widely used solvent in professional dry cleaning. Its strong solvency dissolves oils and greases without damaging most fabrics, and its non-flammability makes it safer in cleaning machines than hydrocarbon solvents. Modern closed-loop dry cleaning machines recover and recycle the solvent, reducing both emissions and operating cost.
Metal Degreasing
In the automotive, aerospace, and metalworking industries, tetrachloroethylene is used to degrease metal parts before machining, plating, painting, or assembly. Its high solvency and fast drying time make it effective for removing oils, waxes, and cutting fluids from precision components.
Consumer and Specialty Products
PERC appears in a limited range of consumer products, including paint strippers, spot removers, and some adhesive products. It is also used as a reaction solvent and as an extraction medium in chemical manufacturing.
Health, Safety, and Environmental Considerations
Because PERC is a volatile organic compound with established health effects, strict controls are required in workplaces and industrial facilities:
Inhalation hazard: vapors can cause dizziness, headache, and central nervous system depression at high concentrations, and prolonged exposure is associated with neurological effects
Cancer classification: tetrachloroethylene is classified as a probable human carcinogen by several health authorities, so exposure should be minimized
Skin and eye contact: the solvent can defat the skin and cause irritation on direct contact
Environmental behavior: releases can contaminate soil and groundwater, and PERC is a regulated pollutant in many jurisdictions
Engineering controls: use closed systems, local exhaust ventilation, vapor recovery, and proper containment to control emissions
Personal protection: wear chemical-resistant gloves, goggles, and appropriate respiratory protection where vapor exposure is possible
In response to these concerns, the dry cleaning industry in several regions is transitioning to alternative technologies and improved machines that sharply reduce PERC use and emission, while metal cleaning operations increasingly evaluate aqueous and other alternative systems.
Storage and Quality Considerations for Buyers
Industrial users should specify the grade, typically dry-cleaning grade or industrial grade, and request a certificate of analysis covering assay value, acidity, water content, and non-volatile residue. PERC should be stored in sealed, corrosion-resistant containers away from strong oxidizers, and any waste solvent should be handled through licensed recovery or disposal services. Suppliers should provide a current safety data sheet and, where required, dangerous goods documentation for transport.
Frequently Asked Questions
Is tetrachloroethylene the same as perchloroethylene? Yes. They are two names for the same chemical, C2Cl4, with the CAS number 127-18-4. PERC and PCE are the common abbreviations.
What is PERC used for? PERC is primarily used as a dry cleaning solvent and as a metal degreasing solvent in automotive and metalworking industries, with smaller uses in paint strippers and spot removers.
What is the CAS number of tetrachloroethylene? The CAS registry number of tetrachloroethylene is 127-18-4.
Is tetrachloroethylene flammable? Tetrachloroethylene is not flammable under normal conditions, which is one reason it is used in dry cleaning. However, it can decompose at high temperatures and should be kept away from hot surfaces and open flames.
What are the health hazards of perchloroethylene? Exposure to PERC vapors can cause dizziness, headache, and central nervous system effects, and long-term exposure is associated with an increased cancer risk, so ventilation and exposure controls are essential.
Is tetrachloroethylene soluble in water? No. Its solubility in water is extremely low, around 0.02 g per 100 mL, and the dense solvent tends to sink below water, which is a key factor in soil and groundwater contamination risks.