What Is Trichloroethylene? Chemical Structure, Functions & Safety
Trichloroethylene was first prepared in 1864. It is man-made and does not exist in the atmosphere naturally. Trichloroethylene emissions can mainly come from three sources: processing, transport, and consumption. It may also be released to the atmosphere by evaporation from and during the manufacture of adhesive glues, paints, coatings, and other chemicals.
In this article, we will study TCE trichloroethylene, trichloroethylene products, TCE in water, and the use of trichloroethylene in detail.
TCE Trichloroethylene
IUPAC name of Trichloroethylene (TCE) is Trichloroethene with a molecular formula of C2HCl3. It is a transparent, mobile, colourless liquid with an ether-like odour.
Density -1.46g/cm3
Molecular weight-131.4 g/mol
Boiling point- 87.2 C
Melting point- -73C
Use of Trichloroethylene
TCE is used in the manufacture of various fluorocarbon refrigerants.
As an efficient degreaser, TCE was used for machinery parts and equipment. It is used to extract grease from fabricated pieces of metal and certain textiles as a solvent (trichloroethylene solvent).
TCE has also been used to clean kerosene-fueled rocket engines (trichloroethylene military use).
It is also used in adhesives, paint removers, fluids for typewriter correction, and spot removers as an ingredient.
Used for the production of 100% ethanol by removing residual water.
Trichloroethylene Structure
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Physical Properties of Trichloroethylene
The Chemical Reaction of Trichloroethylene
4 C2HCl3+ 9 O2 → 8 CO2 + 2 H2O + 6 Cl2
The Industrial History of TCE
It is used as a solvent for organic solvents.
It is used to extract vegetable oil from plant materials.
Used in the food industry for coffee decaffeination and for the preparation of flavouring extract from spices.
It is used as anaesthesia administered with nitrous oxide. It is very effective even in low concentration and thus considered a better anaesthetic than chloroform and ether
TCE in Water and Soil
TCE dissolves only a little in water but can remain in groundwater for a long time.
TCE quickly evaporates from surface water, so it is commonly found as a vapour in the air.
TCE evaporates less easily from the soil than surface water It sticks to particles and remains for a long time.
TCE may stick to particles in water and settle in bottom sediments.
How are People Exposed to TCE?
Breathing air in the home contaminated with TCE vapours.
Drinking, swimming, or showering in water that has been contaminated with TCE.
Contact with soil contaminated with TCE.
Contact with the skin and/or breathing in vapours while using TCE in-home or work
TCE and Human Health
Small amounts of TCE can cause headaches, irritation of the lungs, dizziness, poor coordination, and attention problems.
Impaired heart function, unconsciousness, and death can be caused by breathing large quantities of TCE.
Breathing large quantities of TCE for a long time can cause damage to the nerves, kidneys, and liver.
Nausea, liver damage, unconsciousness, reduced heart function, and death can be caused by consuming significant quantities of TCE.
Drinking large amounts of TCE for long periods of time may cause impaired immune system function, and impaired fetal development (though the extent is not yet clear).
Skin contact with TCE for short periods of time may cause skin rashes.
Did You Know?
Some studies in mice and rats have suggested that high levels of TCE may cause kidney, liver, or lung cancer. Some studies of people exposed over long periods to high levels of TCE in drinking water or in the workplace air have found evidence of increased cancer rates.
The International Agency for Cancer Research has established that TCE is likely to be carcinogenic in humans.
FAQs on Trichloroethylene: Explanation, Uses, and Properties
1. What is trichloroethylene (TCE) and what are its key physical properties?
Trichloroethylene, with the chemical formula C₂HCl₃, is a chlorinated hydrocarbon commonly used as an industrial solvent. It is a type of haloalkene. Its key physical properties include:
Appearance: It is a clear, colourless, volatile liquid.
Odour: It has a sweet, chloroform-like odour.
Density: It is denser than water, which is significant in cases of environmental contamination.
Solubility: It is only slightly soluble in water but is miscible with most organic solvents.
Boiling Point: It has a relatively low boiling point of approximately 87.2 °C, making it highly volatile.
2. What are the primary industrial uses of trichloroethylene?
Due to its excellent solvent properties, trichloroethylene has several industrial applications, although its use has been curtailed due to health concerns. The main uses include:
Metal Degreasing: Its most common application is for vapour degreasing of metal parts in the automotive and electronics industries to remove grease, oils, and other contaminants before surface treatment.
Chemical Intermediate: It is used as a feedstock in the synthesis of other chemicals, particularly fluorocarbon refrigerants like HFC-134a.
Solvent: It acts as an extraction solvent for fats, oils, waxes, and as a solvent in adhesives and paint removers.
Dry Cleaning: Historically, it was used in dry cleaning, but has been largely replaced by safer alternatives.
3. How does exposure to trichloroethylene harm the human body?
Exposure to trichloroethylene, especially over long periods, is associated with significant health risks. It is classified as a known human carcinogen. The primary health effects include:
Nervous System: Short-term exposure can cause dizziness, headaches, confusion, and facial numbness. Chronic exposure can lead to permanent nerve damage.
Cancer Risk: It is strongly linked to an increased risk of kidney cancer, and there is also evidence for risks of non-Hodgkin lymphoma and liver cancer.
Organ Damage: Prolonged exposure can be toxic to the liver and kidneys.
Immune System: TCE has been shown to cause autoimmune diseases like scleroderma, where the body's connective tissues harden.
4. What is the IUPAC name for trichloroethylene, and why is it named that way?
The correct IUPAC name for trichloroethylene is 1,1,2-Trichloroethene. The name is derived based on systematic nomenclature rules:
Ethene: This is the parent name for the two-carbon chain containing a carbon-carbon double bond (C=C).
Trichloro: This prefix indicates the presence of three chlorine (Cl) atoms as substituents.
1,1,2-: These numbers, called locants, specify the position of the chlorine atoms. Numbering the carbon chain from the end that gives the substituents the lowest possible numbers, two chlorine atoms are on carbon-1 and one chlorine atom is on carbon-2.
5. How is trichloroethylene structurally different from trichloromethane (chloroform), and how does this affect their chemical reactivity?
The primary difference lies in their carbon skeletons and saturation. Trichloroethylene (C₂HCl₃) is an unsaturated haloalkene with a two-carbon chain and a C=C double bond. In contrast, trichloromethane (CHCl₃) is a saturated haloalkane based on a single carbon atom. This structural difference dictates their reactivity:
Trichloroethylene, being unsaturated, primarily undergoes electrophilic addition reactions across its double bond.
Trichloromethane, being saturated, primarily undergoes free radical substitution reactions, where its hydrogen atom is replaced.
6. What is the key difference between trichloroethylene and 1,1,1-trichloroethane? Can they be used interchangeably?
While both are chlorinated solvents, they are distinct compounds. Trichloroethylene (TCE) is an alkene (C₂HCl₃) with a double bond. 1,1,1-Trichloroethane (TCA) is an alkane (C₂H₃Cl₃) with only single bonds. Although both were used as industrial degreasers, they were not fully interchangeable. TCA was often preferred for cold cleaning and in adhesives due to its lower toxicity profile compared to TCE. However, TCA was later phased out under the Montreal Protocol for being an ozone-depleting substance, a problem not associated with TCE. Therefore, their applications and environmental impacts are different.
7. What specific properties make trichloroethylene a persistent and dangerous groundwater contaminant?
Trichloroethylene is a notorious groundwater pollutant due to a combination of its physical and chemical properties. Firstly, it is a Dense Non-Aqueous Phase Liquid (DNAPL), meaning it is denser than water and does not dissolve easily. When spilled, it sinks through the soil and water table, pooling at the bottom of aquifers where it is difficult to locate and remove. Secondly, it degrades very slowly under anaerobic (oxygen-free) conditions found deep underground, leading to long-lasting contamination plumes that can spread and affect drinking water sources for decades.
