1,1,1-Trichloroethane

Description

1,1,1-Trichloroethane (1,1,1-TCE) was first identified in 1840 by Henri Victor Regnault, a French chemist and physicist. 1,1,1- TCE is a synthetic chemical that is released to the environment primarily by human industrial activity such as by-process and fugitive emissions during its manufacture, formulation, and use in both consumer and industrial products, which can then undergo thermal and photochemical chlorination. 1,1,1-TCE was originally introduced as a replacement for other chlorinated and flammable solvents like carbon tetrachloride. Although trichloroethane was formerly used extensively in a range of industrial applications and consumer products, including such products as adhesives and adhesive cleaners, lubricants, general purpose liquid cleaners and spray degreasers, oven cleaners, spot removers, shoe polish, and fabric finishes, and as a precursor for hydrofluorocarbons, it is no longer used in common household products. 1,1,1-TCE was one of the compounds addressed by the Montreal Protocol in 1987, which stipulates that the production and consumption of these potentially ozone-depleting substances in the stratosphere were to be phased out. Under this agreement, the final phase out for developed countries for 1,1,1-TCE was 1996, with selected exceptions for existing stocks and essential uses; developing countries have until 2015 for their ban to take effect.

Chemical properties

colourless liquid with a mild ether-like odour. Insoluble in water; soluble in alcohol and ether. Nonflammable.

Chemical properties

1,1,1-Trichloroethane is a colorless liquid. It has an odor similar to chloroform. The Odor Threshold is 120 ppm (NJ) or 400 ppm (NY).

Physical properties

Colorless, watery liquid with a dusty, sooty or polish-type odor similar to chloroform. At 40 °C, the average odor threshold concentration and the lowest concentration at which an odor was detected were 20,000 and 2,200 μg/L, respectively. At 25 °C, the lowest concentration at which a taste was detected was 1,500 μg/L, respectively (Young et al., 1996). The average least detectable odor threshold concentrations in water at 60 °C and in air at 40 °C were 0.47 and 0.32 mg/L, respectively (Alexander et al., 1982).

The Uses of 1,1,1-Trichloroethane

1,1,1-Trichloroethane is used as a cleaningsolvent for cleaning metals and plastic molds.

The Uses of 1,1,1-Trichloroethane

Solvent for cleaning precision instruments, metal degreasing, pesticide, textile processing.

The Uses of 1,1,1-Trichloroethane

METHYL CHLOROFORM is used in industrial applications as a solvent and a degreasing agent.

Definition

ChEBI: A member of the class of chloroethanes carrying three chloro substituents at position 1.

Production Methods

Most commercial methyl chloroform, which is sold under several trade names, contains inhibitors to prevent reaction of the solvent with aluminum and alloys. This reaction produces hydrogen chloride and in confined vessels may produce high pressures.

General Description

A colorless liquid with a sweet, pleasant odor. May irritate skin, eyes and mucous membranes. In high concentrations the vapors may have a narcotic effect. Nonflammable, but may decompose and emit toxic chloride fumes if exposed to high temperatures. Used as a solvent.

Air & Water Reactions

Insoluble in water. Absorbs some water.

Reactivity Profile

1,1,1-Trichloroethane decomposes in the presence of chemically active metals. This includes aluminum, magnesium and their alloys. 1,1,1-Trichloroethane will react violently with dinitrogen tetraoxide, oxygen, liquid oxygen, sodium and sodium-potassium alloys. 1,1,1-Trichloroethane will also react violently with acetone, zinc and nitrates. 1,1,1-Trichloroethane can react with sodium hydroxide. 1,1,1-Trichloroethane is incompatible with strong oxidizers and strong bases. Mixtures with potassium or its alloys are shock-sensitive and may explode on light impact. 1,1,1-Trichloroethane can react with an aqueous suspension of calcium hydroxide, and with chlorine in sunlight. 1,1,1-Trichloroethane will attack some forms of plastics, rubber and coatings. Upon contact with hot metal or on exposure to ultraviolet radiation, 1,1,1-Trichloroethane will decompose to form irritant gases. A cobalt/molybdenum-alumina catalyst will generate a substantial exotherm on contact with its vapor at ambient temperatures. Hazardous reactions also occur with (aluminum oxide + heavy metals). .

Health Hazard

INHALATION: symptoms range from loss of equilibrium and incoordination to loss of consciousness; high concentration can be fatal due to simple asphyxiation combined with loss of consciousness. INGESTION: produces effects similar to inhalation and may cause some feeling of nausea. EYES: slightly irritating and lachrymatory. SKIN: defatting action may cause dermatitis.

Health Hazard

The oral and inhalation toxicity of 1,1,1-trichloroethane is of low order in animalsand humans. It is an anesthetic at highconcentrations. Exposure to its vapors at a1.5% concentration in air may be lethal tohumans. Death may result from anesthesiaand/or cardiac sensitization. Prolonged skincontact may cause defatting and reddeningof eyes. Vapors are irritant to the eyes andmucous membranes.
The acute oral toxicity is low in testanimals. The oral LD50 values in rabbitsand guinea pigs are 5660 and 9470 mg/kg,respectively (NIOSH 1986). The carcino genicity of this compound in animals andhumans is not known.

Fire Hazard

Special Hazards of Combustion Products: Toxic and irritating gases are generated in fires.

Industrial uses

Methyl chloroform is a versitile, all purpose solvent, popular with industry because of its powerful cleaning properties, low flammability, and low relative toxicity. It was introduced in the mid 1950s as a cold cleaning solvent substitute for carbon tetrachloride. Today, methyl chloroform is used primarily for vapor degreasing and cold cleaning of fabricated metal parts and other materials. The chemical also is used in fluoropolymer synthesis, as a solvent in adhesive and aerosol formulations, for the production of certain coatings and inks, for a variety of textile applications, and for dry cleaning leather and suede garments. Methyl chloroform is a member of a family of saturated aliphatic halogenated hydrocarbons.
Metal vapor degreasing is an important process in industrial manufacture, used to remove oils and oil-borne soils (i.e., chips, metal fines, and fluxes) from objects that have been stamped, machined, welded, soldered, molded, or diecast. Vapor degreased parts vary from tiny transistors to aircraft and spacecraft assemblies.
Methyl chloroform is an excellent solvent for the cold (room temperature) cleaning of a wide variety of manufacturing equipment and products including yarns, threads, finished cloth, reinforced fiberglass, plastics, and common and exotic metals. The solvent removes most greases, oils, lubricants, waxes, adhesives, inks, fluxes, paints, stamping and drawing compounds, tars, and other soils.
The main reasons for the use of methyl chloroform in formulations for urethane and neoprene/phenolic contact adhesives, mastics, sealants, and natural rubber tire repair cements are its ability to substantially reduce flammability, its nonphotochemical reactivity, and the favorable characteristics of the resulting adhesive formulation.
The main applications of methyl chloroform in the electronics industry are in circuit board fabrication, where it is used to develop dry film photoresist, and in the semiconductor industry where it is used for secondary cleaning.
Methyl chloroform serves as a raw material for the manufacture of polyvinylidene fluoride fluoropolymer. It also can be used as a raw material for the production of certain hydrochlorofluorocarbons having relatively short atmospheric residence times.
In the coatings manufacturing industry, methyl chloroform is used as a solvent in the formulation of protective and decorative coatings and as a thinner to reduce the viscosity of high-solid content coatings for spray application. The chemical also can be used in the production of rotogravure and flexographic inks. In addition to the above uses, methyl chloroform is used to dry clean leather and suede products and to clean motion picture film.

Contact allergens

Trichloroethane is a solvent that has wide applications in industry, such as for cold type metal cleaning and in cleaning plastic molds. It is mainly an irritant, but can also provoke allergic contact dermatitis.

Safety Profile

Poison by intravenous route. Moderately toxic by ingestion, inhalation, skin contact, subcutaneous, and intraperitoneal routes. An experimental teratogen. Human systemic effects by ingestion and inhalation: conjunctiva irritation, hallucinations or distorted perceptions, motor activity changes, irritability, aggression, hypermotility, diarrhea, nausea or vomiting and other gastrointestinal changes. Experimental reproductive effects. Questionable carcinogen. Mutation data reported. A human skin irritant. An experimental skin and severe eye irritant. Narcotic in high concentrations. Causes a proarrhythmic activity that sensitizes the heart to epinephrine-induced arrhythmias. This sometimes will cause cardlac arrest, particularly when this material is massively inhaled as in drug abuse for euphoria.
Under the proper conditions it can undergo hazardous reactions with aluminum oxide + heavy metals, dinitrogen tetraoxide, inhbitors, metals (e.g., magnesium, aluminum, potassium, potassium-sodium alloy), sodium hydroxide, N2O4, oxygen. When heated to decomposition it emits toxic fumes of Cl-. Used as a cleaning solvent, as a chemical intermediate to produce vinylidene chloride, and as a propellant in aerosol cans.

Potential Exposure

1,1,1-Trichloroethane is used as a cleaning solvent, chemical intermediate for vinylidene chloride. In liquid form it is used as a degreaser and for cold cleaning, dip-cleaning; and bucket cleaning of metals. Other industrial applications of 1,1,1-trichlroethane’s solvent properties include its use as a dry-cleaning agent; a vapor degreasing agent; and a propellant. In recent years, 1,1,1-trichloroethane has found wide use as a substitute for carbon tetrachloride.

Carcinogenicity

IRIS provides a cancer descriptor of “inadequate information to assess carcinogenic potential.” This is based on inconclusive epidemiologic studies. A 2 year inhalation bioassay showed no treatment- related increase in tumors in rats and mice. The two available oral cancer bioassays in rats and mice are inadequate for evaluation of cancer potential. The compound has been shown to be rather negative in short-term tests for genotoxicity.
NCI tested rats and mice by oral and inhalation routes, but the results were questionable. Quast et al. exposed 96 Sprague–Dawley rats of both sexes to 875 or 1750 ppm 1,1,1-trichloroethane vapor for 6 h/ day, 5 days/week for 12 months, followed by an additional 19 month observation period. The only significant sign of toxicity was an increased incidence of focal hepatocellular alterations in female rats at the highest dosage. Neither was it evident that a maximum tolerated dose was used nor was a range-finding study conducted. No significant dose-related neoplasms were reported, but these dose levels were below those used in the NCI study.
In another study, Quast et al. used an inhibited formulation of 1,1,1-trichloroethane. Fischer 344 rats and B6C3F1 mice of both sexes were exposed to 0, 150, 500, or 1500 ppm 6 h/day, 5 days/week for 2 years. The authors indicate that there were no indications of an oncogenic effect on rats or mice following 2 years of exposure to the 1,1,1- trichloroethane formulation and a NOAEL of 500 ppm for adverse effect of any kind. The ATSDR reviewed this information (52) and determined that the study adequately demonstrated negative evidence of carcinogenicity in animals by lifetime inhalation up to 1500 ppm.

Environmental Fate

Biological. Microbial degradation by sequential dehalogenation under laboratory conditions produced 1,1-dichloroethane, cis- and trans-1,2-dichloroethylene, chloroethane, and vinyl chloride. Hydrolysis products via dehydrohalogenation included acetic acid, 1,1-dichloroethylene (Dilling et al., 1975; Smith and Dragun, 1984), and HCl (Dilling et al., 1975). The reported halflives for this reaction at 20 and 25 °C are 0.5 to 2.5 and 1.1 yr, respectively (Vogel et al., 1987; ten Hulscher et al., 1992).
Groundwater. Under aerobic conditions, 1,1,1-trichloroethane slowly degraded to 1,1- dichloroethane (Parsons and Lage, 1985; Parson et al., 1985). Based on a study conducted by Bouwer and McCarty (1984), the estimated half-life of 1,1,1-trichloroethane in groundwater three months after injection was 200–300 d.
Surface Water. Estimated half-lives of 1,1,1-trichloroethane (4.3 μg/L) from an experimental marine mesocosm during the spring (8–16 °C), summer (20–22 °C), and winter (3–7 °C) were 24, 12, and 11 d, respectively (Wakeham et al., 1983).
Photolytic. Reported photooxidation products include phosgene, chlorine, HCl, and carbon dioxide (McNally and Grob, 1984). Acetyl chloride (Christiansen et al., 1972) and trichloroacetaldehyde (U.S. EPA, 1975) have also been reported as photooxidation products. 1,1,1-Trichloroethane may react with OH radicals in the atmosphere producing chlorine atoms and chlorine oxides (McConnell and Schiff, 1978). The rate constant for this reaction at 300 K is 9.0 x 10-9 cm³/molecule?sec (Hendry and Kenley, 1979).
Chemical/Physical. The evaporation half-life of 1,1,1-trichloroethane (1 mg/L) from water at 25 °C using a shallow-pitch propeller stirrer at 200 rpm at an average depth of 6.5 cm was 18.7 min (Dilling, 1977).

Shipping

UN2831 1,1,1-Trichloroethane, Hazard Class: 6.1; Labels: 6.1-Poisonous materials.

Purification Methods

Wash it successively with conc HCl (or conc H2SO4), aqueous 10% K2CO3 (Na2CO3), aqueous 10% NaCl, dry it with CaCl2 or Na2SO4, and fractionally distil it. It can contain up to 3% dioxane as preservative. This is removed by washing successively with 10% aqueous HCl, 10% aqueous NaHCO3 and 10% aqueous NaCl, and distilling over CaCl2 before use. [Beilstein 1 IV 138.]

Toxicity evaluation

The central nervous system (CNS) is the most sensitive target for 1,1,1-TCE, following inhalation exposure in animals and humans. The CNS-depressant effects are thought to involve interactions of the parent compound with lipids and/or proteins in neural membranes. In general, the lipophilic nature of 1,1,1-TCE allows it to cross the blood–brain barrier readily and partition into lipids in neuronal membranes, which ultimately interfere with neural membrane function, bringing about CNS depression, behavioral changes, and anesthesia.
High 1,1,1-TCE levels also produce depression of respiration and blood pressure and cardiac arrhythmias by sensitizing the heart to endogenous epinephrine. 1,1,1-TCE is a weak hepatotoxicant, producing mild effects on the liver at relatively high levels. The arrhythmogenic effects are thought to be produced by the parent compound. It is uncertain whether the hepatotoxic effects of 1,1,1-TCE are due to the parent compound or are mediated by metabolites such as trichloroacetic acid and/or reactive intermediates. In addition to the depressive effect on the heart, membrane alterations are also thought to play an important role in the occurrence of arrhythmogenic effects. Incorporation of 1,1,1-TCE into the membrane of cardiac myocytes near the gap junction is thought to explain the observed inhibition of gap junction intercellular communication in cardiac myocytes. Most of the effects of 1,1,1-TCE are hypothesized to be produced by the parent compound, by interfering with the function of mitochondrial and cellular membranes.

Incompatibilities

Not flammable under normal conditions. However, in close or closed spaces, it may form a dangerously explosive atmosphere. See also fireextinguishing section. Strong caustics; strong oxidizers; chemically active metals, such as aluminum, magnesium powder; sodium, potassium. Reacts slowly with water forming hydrochloric acid. Upon contact with hot metal or exposure to UV radiation, it will decompose to form hydrochloric acid, phosgene and dichloroacetylene. Forms shocksensitive mixtures with potassium or its alloys. Attacks natural rubber.

Waste Disposal

Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal. Incineration, preferably after mixing with another combustible fuel. Care must be exercised to assure complete combustion to prevent the formation of phosgene. An acid scrubber is necessary to remove the halo acids produced. As an alternative to disposal, trichloroethane may be recovered from waste gases and liquids from various processes and recycled.