CHLOROETHANE

Overview

Chloroethane (also known as ethyl chloride) is a chemical compound with chemical formula C2H5Cl, and has been widely used in producing tetraethyllead, a gasoline additive. It is a colorless, flammable gas or refrigerated liquid with a faintly sweet odor.
Ethyl chloride is used in the production of ethyl cellulose, use as a solvent, refrigerant, and topical anesthetic, in the manufacture of dyes, chemicals, and pharmaceuticals, and as a medication to alleviate pain associated with insect burns and stings.^[1]
In the past, ethyl chloride was used in the production of tetraethyl lead, an anti-knock additive to leaded gasoline. Government-mandated reduction in the amount of lead additives used in gasoline in the United States and a shift to the use of unleaded gasoline has caused a drastic reduction in the amount of ethyl chloride required for the production of tetraethyl lead.^[1]

Chemical Properties

Ethyl chloride is a colorless gas with an ethereal odor^[1,6]. Ethyl chloride has an odor threshold of 4.2 parts per million (ppm)^[7]. Ethyl chloride is slightly soluble in water^[1].
The chemical formula for ethyl chloride is C2H5Cl, and it has a molecular weight of 64.52 g/mol^[1,3]. The vapor pressure for ethyl chloride is 1,008 mm Hg at 20°C, and the log octanol/water partition; coefficient (log Kow) is 1.43; coefficient (log Kow) is 1.43.^[1]

Production

The dominant process for production of ethyl chloride in the USA involves the addition of anhydrous hydrogen chloride to ethylene in the presence of an aluminium chloride catalyst. The hydrochlorination is a liquidphase reaction, carried out at about 40°C. Reacted products are fed into a flash evaporator column, where ethyl chloride is separated from less volatile compounds and then purified by fractionation. Hydrochlorination of ethanol has not been used for US ethyl chloride production since 1980, and chlorination of ethane (catalytically, electrolytically, thermallyor photochemically) has not been used at any production facility in the USA since 1974. Ethyl chloride is also obtained as a by-product from the production of vinyl chloride^[1] or chlorofluorocarbon, although this method accounts for only a small amount.

Application

Ethyl chloride is used in the manufacture of tetraethyllead and as an alkylating agent in the production of ethylcellulose (which is used in paper coatings, printing inks, films, adhesives and moulded plastics), ethylhydroxyethylcellulose, and some pharmaceuticals and as a foam-blowing agent in the manufacture of polystyrene. It is used as a local anaesthetic because of its rapid cooling effect as it vaporizes^[1]. Historical and minor uses Include use in organic synthesis, as an alkylating agent in the production of aluminium alkyls and other metal alkyls and as a solvent for phosphorus, sulfur, fats, oils, resins and waxes.

Source and exposure

Sources of possible ethyl chloride exposure include the inhalation of contaminated air and ingestion of contaminated drinking water at very low levels. The general population can be exposed to ethyl chloride by skin contact with consumer products that contain ethyl chloride such as solvents and refrigerants. Occupational exposure by inhalation or dermal contact with ethyl chloride can occur in industries such as medical and health services; automotive dealers and service stations; wholesale trade, electric, gas, and sanitary services; machinery (except electrical) and special trade contractors; fabricated metal productions; printing and publishing; painting; rubber and plastic products; and food.^[1] Although chemists use tests such as gas chromatography to measure ethyl chloride in blood, milk, or urine, no commonly used medical tests are available to determine whether or not a person has been exposed to ethyl chloride.^[1]

Toxicity

Acute Effects
Acute inhalation exposure to high levels of ethyl chloride in humans has resulted in temporary feelings of drunkenness, dizziness, lack of muscle coordination and unconsciousness. Accidental death has resulted from its former medical use as an anesthetic during major surgery.^[1,2] Tests involving acute exposure of animals in rats and mice have shown ethyl chloride to have low toxicity from inhalation exposure.^[3]
Chronic Effects
Neurological symptoms including ataxia, tremors, speech difficulties, slowed reflexes, involuntary eye movement, and hallucinations, and liver effects were reported in individuals who purposely inhaled very high concentrations of ethyl chloride for a few months.^[4]
Some animal studies indicate effects on the lungs, liver, kidneys, and heart due to ethyl chloride exposure via inhalation.^[1] The Reference Concentration (RFC) for ethyl chloride is 10 milligrams per cubic meter (mg/m3) based on delayed fetal ossification in mice. The RFC is an estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups), which is likely to be without appreciable risk of deleterious noncancer effects during a lifetime. It is not a direct esimator of risk but rather a reference point to gauge the potential effects. At exposures increasingly greater than the RFC, the potential for adverse health effects increases. Lifetime exposure above the RFC does not imply that an adverse health effect would necessarily occur.^[4]
EPA has medium confidence in the study on which the RFC is based because, although the study is well conducted, it does not establish a firm concentration-response relationship with an adverse effect and was not performed at levels eliciting maternal toxicity; medium confidence in the database due to the lack of a multigenerational reproductive study and a developmental study in a second species; and, consequently, medium confidence in the RFC.^[4] EPA has not established a Reference Dose (RfD) for ethyl chloride.^[4] Reproductive/Developmental Effects
No studies were located regarding reproductive or developmental effects following ethyl chloride inhalation exposure in humans.
Several animal studies found no reproductive effects caused by ethyl chloride exposure. An animal study reported a decrease in uterine weights, while another study reported minimal evidence of fetotoxicity (increase in centers of unossified bones of the skull) from inhalation exposure to ethyl chloride.^[1]
Cancer Risk
There are no human cancer data available for ethyl chloride. A 2-year bioassay performed by the NTP indicated that inhaled ethyl chloride is carcinogenic in female mice and may be carcinogenic in rats. Female mice experienced a significant increase in the incidence of uterine tumors and hepatocellular tumors, but the data on male mice were considered inadequate because of a low survival rate. Benign and malignant epithelial neoplasms of the skin, and three uncommon malignant astorcyomas of the brain, were reported in male and female rats, respectively.^[5] EPA has not classified ethyl chloride for carcinogenicity.^[4]

References

1. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Ethyl chloride (Update).Public Health Service, U.S. Department of Health and Human Services, Atlanta, GA. 1998.
2. U.S. Department of Health and Human Services. Hazardous Substances Data Bank (HSDB, online database). National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993.
3. U.S. Department of Health and Human Services. Registry of Toxic Effects of Chemical Substances (RTECS, online database). National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993.
4. U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS) on Ethyl Chloride. National Center for Environmental Assessment, Office of Research and Development, Washington, DC. 1999.
5. National Toxicology Program. Toxicology and Carcinogenesis Studies of Ethyl chloride (Ethyl Chloride) (CAS No. 75-00-3) in F344/N Rats and B6C3F1 Mice (Inhalation Studies). TR No. 346. U.S. Department of Health and Human Services, Public Health Service, National Institutes of Health, Bethesda, MD. 1989.
6. The Merck Index. An Encyclopedia of Chemicals, Drugs, and Biologicals. 11th ed. Ed. S. Budavari. Merck and Co. Inc., Rahway, NJ. 1989.
7. J.E. Amoore and E. Hautala. Odor as an aid to chemical safety: Odor thresholds compared with threshold limit values and volatilities for 214 industrial chemicals in air and water dilution. Journal of Applied Toxicology, 3(6):272-290. 1983.

Description

Ethyl chloride is a colorless gas or liquid(below 12℃) with a pungent, ether-like odor and a burningtaste. Shipped as a liquefied compressed gas. Molecularweight 5 64.52; Specific gravity (H2O:1) = 0.92 (liquid at0℃); Boiling point = 12.2℃; Freezing/Meltingpoint = 2138.9; Vapor pressure = 1000 mmHg at 20℃;Flash point = -50℃ (liquid); Autoignitiontemperature = 519℃. Explosive limits: LEL = 3.8%;UEL = 15.4%. Hazard Identification (based on NFPA-704M Rating System): Health 1, Flammability 4, Reactivity 0.Slightly soluble in water; solubility = 0.6%.

Chemical Properties

colourless gas

Chemical Properties

Ethyl chloride is a colorless gas or liquid (below 12℃) with a pungent, ethereal odor and a burning taste. Shipped as a liquefied compressed gas.

Physical properties

Clear, colorless gas or liquid with a pungent or faint, sweetish ether-like odor. When spilled, ethyl chloride evaporates quickly. Odor threshold concentration is 4.2 ppm (quoted, Amoore and Hautala, 1983).

Uses

Ethyl chloride is used as a refrigerant, as asolvent, in the manufacture of tetraethyl lead,and as an alkylating agent. It is also used asa topical anesthetic.

Uses

Chloroethane is a useful reactant in organic synthesis.

Uses

Refrigerant, solvent, alkylating agent, starting point in the manufacture of tetraethyl lead: US 1907701 (1933).

Uses

Ethyl chloride is used as synthetic gums and thickeners in the lacquer and plastics industries. Ethyl chloride is also used in the Friedel-Crafts alkylation of benzene and other aromatics. Additional uses include solvent, refrigerant, heat-transfer medium, aerosol propellant and anesthetic.

Definition

A highly reactive manmade volatile organic com- pound that is highly reactive in the atmosphere. It readily reacts with oxidizing agents to release the chlorine atoms which, circulate and cause tropo- spheric ozone to decompose.

Indications

Chlorethane (ethyl chloride) is a highly flammable liquid that acts as a topical vapocoolant to control pain associated with minor surgical procedures.When applied as a spray, the product produces freezing of superficial tissues to ?20?C, which results in insensitivity of peripheral nerve endings and local anesthesia that is maintained up to 1 minute. Other coolant sprays can be used with the same effect.

Production Methods

Ethyl Chloride can be synthesized by treatment of ethyl alcohol with HCl, cleavage of diethylether with HCl in the presence of a catalyst (ZnCl2), chlorination of ethane or hydrochlorination of ethylene. The latter is the choice of industry. The reaction is carried out at 125 °F and 125 psi in the presence of AlCl3, which is dissolved in ethyl chloride.

Definition

A gaseous compound made by the addition of hydrogen chloride to ethene. It is used as a refrigerant and a local anesthetic.

General Description

A clear colorless gas with a pungent odor. Flash point -58°F. Boiling point 54°F. Less dense than water and insoluble in water. Vapors are heavier than air. Under prolonged exposure to fire or heat the containers may rupture violently and rocket.Ethyl chloride is used as a solvent for oils,resins,and waxes. It is used in medicine and as an intermediate in synthesis.

Air & Water Reactions

Highly flammable. Insoluble in water.

Reactivity Profile

CHLOROETHANE is heat sensitive. CHLOROETHANE will hydrolyze in the presence of alkalis and water. CHLOROETHANE reacts with water or steam to produce toxic and corrosive fumes. CHLOROETHANE can also react vigorously with oxidizing materials. The vapor forms highly flammable mixtures with air. A mixture of CHLOROETHANE with potassium is shock-sensitive. Contact with chemically active metals such as Na, K, Ca, powdered Al, Zn and Mg may result in violent reactions.

Hazard

Highly flammable, severe fire and explosion risk; flammable limits in air 3.8–15.4%. Irritant to eyes. Questionable carcinogen.

Health Hazard

Exposure to high levels of ethyl chloride cancause stupor, eye irritation, incoordination,abdominal cramps, anesthetic effects, cardiacarrest, and unconsciousness. No toxic effectswere noted at a concentration of 10,000 ppm.A 45-minute exposure to a 4% concentrationof ethyl chloride in air was lethal to guineapigs. A brief exposure for 5 to 10 minutes toa concentration of 10% of the gas was notfatal to the test animals but caused kidneyand liver damage. In humans narcotic effectsmay occur after a few inhalations of 5–10%concentrations of the gas. Irritant effectson the eyes, skin, and respiratory tract aremild. Skin contact with the liquid can causefrostbite due to cooling by rapid evaporation.
LC50 value, inhalation (rats): 60,000 ppm/2 hr.

Health Hazard

Vapor causes drunkenness, anesthesia, possible lung injury. Liquid may cause frostbite on eyes and skin.

Chemical Reactivity

Reactivity with Water: No reaction; Reactivity with Common Materials: No reaction; Stability During Transport: Stable; Neutralizing Agents for Acids and Caustics: Not pertinent; Polymerization: Not pertinent; Inhibitor of Polymerization: Not pertinent.

Safety Profile

Suspected carcinogen with experimental carcinogenic and neoplastigenic data. Mildly toxic by inhalation. An irritant to sh, eyes, and mucous membranes. The liquid is harmful to the eyes and can cause some irritation. In the case of guinea pigs, the symptoms attending exposure are similar to those caused by methyl chloride, except that the signs of lung irritation are not as pronounced. It gives some warning of its presence because it is irritating, but it is possible to tolerate exposure to it until one becomes unconscious. It is the least toxic of all the chlorinated hydrocarbons. It can cause narcosis, although the effects are usually transient. A very dangerous fire hazard when exposed to heat or flame; can react vigorously with oxidizing materials. Severe explosion hazard when exposed to flame. Reacts with water or steam to produce toxic and corrosive fumes. Incompatible with potassium. To fight fire, use carbon dioxide. When heated to decomposition it emits toxic fumes of phosgene and Cl-. See also CHLORINATED HYDROCARBONS, ALIPHATIC.

Potential Exposure

Ethyl chloride is used as an ethylating agent in the manufacture of tetraethyl lead, dyes, drugs, and ethyl cellulose; as a pharmaceutical, solvent; alkylating agent; as a refrigerant and as a local anesthetic (freezing).

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit

Carcinogenicity

The EPA has not made a carcinogenicity assessment as yet. However, the State of California reviewed the carcinogenicity information.
CalEPA, using the NTP study, developed a cancer potency estimate of 4.7E-3 per mg/kg/day and defined a No Significance Risk Level (NSRL) of 1 50 μg/day.
Increased cancer of the uterus of female mice has been produced by exposure to 15,000 ppm, but lower concentrations have not been studied. Rats and mice were exposed to 0 or 15,000 ppm of ethyl chloride in an NTP 2-year study with mixed results. Results in male rats were considered equivocal based on a combined total of five skin tumors versus none in the control male rats. Likewise, female rats’ results were considered equivocal because three astrocytomas were found versus none in the female control rats. The male mouse group had such poor survival that it was deemed an inadequate study although combined alveolar/bronchiolar adenomas and carcinomas were reported (10/48 versus 5/50 in the control male rats). Female mice exposed to 15,000 ppm had clear evidence of an effect, for 43/50 mice had endometrial uterine carcinomas versus 0/49 in the female control mice. In addition, there was a suggestion of an increase in combined hepatocellular adenomas and carcinomas in the female mice (8/48 exposed versus 3/49 control). There is clear evidence for carcinogenicity in female B6C3F1 mice and equivocal evidence in male and female F344/N rats (high incidence of uterine carcinomas.)

Environmental Fate

Photolytic. The rate constant for the reaction of chloroethane and OH radicals in the atmosphere at 300 K is 2.3 x 10^-11 cm³/molecule?sec (Hendry and Kenley, 1979). At 296 K, a photooxidation rate constant of 3.9 x 10^-13 cm³/molecule?sec was reported (Howard and Evenson, 1976). The estimated tropospheric lifetime is 14.6 d (Nimitz and Skaggs, 1992).
Chemical/Physical. Under laboratory conditions, chloroethane hydrolyzed to ethanol (Smith and Dragun, 1984). An estimated hydrolysis half-life in water at 25 °C and pH 7 is 38 d, with ethanol and HCl being the expected end-products (Mabey and Mill, 1978). Based on a measured hydrolysis rate constant of 5.1 x 10^-7 at 25 °C and pH 7, the half-life is 2.6 yr (Jeffers and Wolfe, 1996).
In air, formyl chloride is the initial photooxidation product (U.S. EPA, 1985). In the presence of water, formyl chloride hydrolyzes to HCl and carbon monoxide (Morrison and Boyd, 1971).
Burns with a smoky, greenish flame releasing hydrogen chloride (Windholz et al., 1983).
In the laboratory, the evaporation half-life of chloroethane (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 23.1 min (Dilling, 1977).
At influent concentrations of 1.0, 0.1, and 0.01 mg/L, the GAC adsorption capacities at pH 5.3 were 0.59, 0.07, and 0.007 mg/g, respectively (Dobbs and Cohen, 1980).

Solubility in water

Soluble in ethanol, ether (U.S. EPA, 1985); miscible with chlorinated hydrocarbons such as chloroform, carbon tetrachloride, and tetrachloroethane.

storage

Color Code—Red Stripe: Flammability Hazard:Store separately from all other flammable materials. Priorto working with this chemical you should be trained on itsproper handling and storage. Before entering confined spacewhere this chemical may be present, check to make surethat an explosive concentration does not exist. Ethyl chloride must be stored to avoid contact with oxidizers (such asperoxides, chlorates, perchlorates, nitrates, and permanganates) or chemically active metals (such as sodium, potassium, calcium, powdered aluminum, zinc, and magnesium)because violent reactions occur. Store in tightly closed containers in a cool, well-ventilated area away from heat.Sources of ignition, such as smoking and open flames, areprohibited where ethyl chloride is handled, used, or stored.Metal containers used in the transfer of 5 gallons or more ofethyl chloride should be grounded and bonded. Drums mustbe equipped with self-closing valves, pressure vacuumbungs, and flame arresters. Use only nonsparking tools andequipment, especially when opening and closing containersof ethyl chloride. Procedures for the handling, use, and storage of cylinders should be in compliance with OSHA1910.101 and 1910.169, as with the recommendations ofthe Compressed Gas Association.

Shipping

UN1037 Ethyl chloride, Hazard Class: 2.1; Labels: 2.1-Flammable gas. Cylinders must be transported in a secure upright position, in a well-ventilated truck. Protect cylinder and labels from physical damage. The owner of the compressed gas cylinder is the only entity allowed by federal law (49CFR) to transport and refill them. It is a violation of transportation regulations to refill compressed gas cylinders without the express written permission of the owner.

Purification Methods

Pass ethyl chloride through absorption towers containing, successively, conc H2SO4, NaOH pellets, P2O5 on glass wool, or soda-lime, CaCl2, P2O5. Condensed it into a flask containing CaH2 and fractionally distil it. It has also been purified by illumination in the presence of bromine at 0o using a 1000W lamp, followed by washing, drying and distilling. [Beilstein 1 IV 124.]

Incompatibilities

Flammable gas. Slow reaction with water; forms hydrogen chloride gas. Contact with moisture (water, steam) forms hydrochloric acid and/or fumes of hydrogen chloride. May accumulate static electrical charges, and may cause ignition of its vapors. May form explosive mixture with air. Contact with chemically active metals: aluminum, lithium, magnesium, sodium, potassium, zinc may cause fire and explosions. Attacks some plastics and rubber.

Waste Disposal

Return refillable compressed gas cylinders to supplier. 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.