1,1,1-trichloroethane

**Properties**
General
Name	1,1,1-trichloroethane
Chemical formula	C H₃CCl₃
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
Δ_fH⁰_gas	? kJ/mol
Δ_fH⁰_liquid	? kJ/mol
Δ_fH⁰_solid	? kJ/mol
S⁰_{gas, 1 bar}	? J/mol·K
S⁰_{liquid, 1 bar}	? J/mol·K
S⁰_solid	? 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. Disclaimer and references

The chemical compound 1,1,1-trichloroethane is a chlorinated hydrocarbon that was until recently widely used as an industrial solvent. Other names for it include methyl chloroform, chlorothene, and the trade name Solvent 111.

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.

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, iron(III) chloride, or zinc chloride. Its chemical equation is

CH₂=CHCl + HCl → CH₃CHCl₂

The 1,1-dichloroethane is then converted to 1,1,1-trichloroethane by reaction with chlorine under ultraviolet irradiation

CH₃CHCl₂ + Cl₂ → CH₃CCl₃ + HCl

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 an iron(III) 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.

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