1,1,1-trichloroethane
From Wikipedia, the free encyclopedia.
| General | |
|---|---|
| Name | 1,1,1-trichloroethane |
| Chemical formula | CH3CCl3 |
| Appearance | Colorless liquid |
| Physical | |
| Formula weight | 133.4 amu |
| Melting point | 240 K (-33 °C) |
| Boiling point | 347 K (74 °C) |
| Density | 1.32 ×103 kg/m3 (liquid) |
| Solubility | insoluble in water |
| Thermochemistry | |
| ΔfH0gas | ? kJ/mol |
| ΔfH0liquid | ? kJ/mol |
| ΔfH0solid | ? kJ/mol |
| S0gas, 1 bar | ? J/mol·K |
| S0liquid, 1 bar | ? J/mol·K |
| S0solid | ? J/mol·K |
| Safety | |
| Ingestion | May cause nausea, vomiting, cardiac irregularities. |
| Inhalation | Can cause dizziness, headache, and unconsciousness. Irritant to the upper respiratory tract. |
| Skin | Possible irritant. Possible sensitizer, leading to allergic response after re-exposure. |
| Eyes | Causes severe irritation and swelling. |
| More info | Hazardous Chemical Database |
| SI units were used where possible. Unless otherwise stated, standard conditions were used. | |
1,1,1-trichloroethane was first produced by the French chemist Henri Victor Regnault in 1840. It was produced in large quantities by the chemical industry beginning in the mid-1950s and continuing through 1995. Today, it is banned by the Montreal Protocol.
| Table of contents |
|
2 Uses 3 Safety |
Production
Industrially, 1,1,1-trichloroethane is usually produced in a two-step process from vinyl chloride. In the first step, vinyl chloride reacts with hydrogen chloride at 20-50°C to produce 1,1-dichloroethane. This reaction is catalyzed by one of aluminum chloride, ferric chloride, or zinc chloride. Its chemical equation is
The 1,1-dichloroethane is then converted to 1,1,1-trichloroethane by reaction with chlorine under ultraviolet irradiation This reaction proceeds at 80-90% yield, and the hydrogen chloride byproduct can be recycled to the first step in the process. The major side-product is the related compound 1,1,2-trichloroethane, from which the 1,1,1-trichloroethane can be separated by distillation.A somewhat smaller amount of 1,1,1-trichloroethane is produced from the reaction of vinylidene chloride and hydrogen chloride in the presence of a ferric chloride catalyst:
- CH2=CCl2 + HCl → CH3CCl3
Uses
1,1,1-trichlorethane is an excellent solvent for many organic materials and also one of the least toxic of the chlorinated hydrocarbons. Prior to the Montreal Protocol, it was used for cleaning metal parts and circuit boards, as a photoresist solvent in the electronics industry, as an aerosol propellant, and as a solvent for inks, paints, adhesives, and other coatings.
The Montreal Protocol targeted 1,1,1-trichloroethane as one of those compounds responsible for ozone depletion and banned its use beginning in 1996. Since then, its manufacture and use has been phased out throughout most of the world.
Safety
Although not as toxic as many similar compounds, inhaled or ingested 1,1,1-trichloroethane does act as a central nervous system depressant and can cause effects similar to those of intoxication, including dizziness, confusion, and in sufficiently high concentrations, unconsciousness and death.
Prolonged skin contact with the liquid can result in the removal of fats from the skin, resulting in chronic skin irritation.
Studies on laboratory animals have shown that 1,1,1-trichloroethane is not retained in the body for long periods of time. However, chronic exposure has been linked to abnomalities in the liver, kidneys, and heart. Pregnant women should avoid exposure, as the compound has been linked to birth defects in laboratory animals.