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Urethane ( CASNO:51-79-6 )

Identification and Related Records
CAS Registry number:
Urethane (Ethyl Carbamate)
Ethyl carbamate
Poly(carbonate urethane)
Molecular Formula:
Molecular Weight:
Canonical SMILES:
Chemical and Physical Properties
white crystalline powder
Melting Point:
Boiling Point:
Refractive Index:
1.4144 (51 C)
Flash Point:
slightly soluble
slightly soluble
Colorless, columnar crystals or white, granular powder
Prisms from benzene and toluene
Stable. Incompatible with strong acids, strong bases, strong oxidizing agents.
Storage temp:
Keep away from heat, sparks, and flame. Keep away from sources of ignition. Store in a tightly closed container. Store in a cool, dry, well-ventilated area away from incompatible substances.
Spectral properties:
Index of refraction: 1.4144 at 51 deg C/D
IR: 5961 (Coblentz Society Spectral Collection)
NMR: 245 (Sadtler Research Laboratories Spectral Collection)
C13NMR: 37 (Johnson and Jankowski carbon 13 NMR Spectra. John Wiley and Sons, New York.)
MASS: 707 (NIST/EPA/MSDC Mass Spectral Database. 1990 version)
Computed Properties:
Molecular Weight:89.09318 [g/mol]
Molecular Formula:C3H7NO2
H-Bond Donor:1
H-Bond Acceptor:2
Rotatable Bond Count:2
Tautomer Count:2
Exact Mass:89.047678
MonoIsotopic Mass:89.047678
Topological Polar Surface Area:52.3
Heavy Atom Count:6
Formal Charge:0
Isotope Atom Count:0
Defined Atom Stereocenter Count:0
Undefined Atom Stereocenter Count:0
Defined Bond Stereocenter Count:0
Undefined Bond Stereocenter Count:0
Covalently-Bonded Unit Count:1
Feature 3D Acceptor Count:1
Feature 3D Donor Count:1
Effective Rotor Count:2
Conformer Sampling RMSD:0.4
CID Conformer Count:9
Safety and Handling
Hazard Codes:
Risk Statements:
Safety Statements:
Hazard Codes of Urethane (CAS NO.51-79-6): T
Risk Statements: 45 
R45: May cause cancer.
Safety Statements: 53-45-9 
S53: Avoid exposure - obtain special instructions before use. 
S45:I n case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) 
S9: Keep container in a well-ventilated place.
WGK Germany: 3
RTECS: FA8400000
Confirmed carcinogen with experimental carcinogenic, neoplastigenic, and tumorigenic data. A transplacental carcinogen. Moderately toxic by ingestion, intraperitoneal, subcutaneous, intramuscular, parenteral, and intravenous routes. An experimental teratogen. Experimental reproductive effects. Human mutation data reported. Causes depression of bone marrow and occasionally focal degeneration in the brain. Can also produce central nervous system depression, nausea and vomiting. Has been found in over 1000 beverages sold in the United States. The most heavily contaminated liquors are bourbons, sherries, and fruit brandies (some had 1000 to 12,000 ppb urethane). Many whiskeys, table and dessert wines, brandies, and liqueurs contain potentially hazardous amounts of urethane. The allowable limit for urethane in alcoholic beverages is 125 ppb. It is formed as a side product during processing.  

Hot aqueous acids or alkalies decompose urethane to ethanol, carbon dioxide, and ammonia. Reacts with phosphorus pentachloride to form an explosive product. When heated it emits toxic fumes of NOx. Used as an intermediate in the manufacture of pharmaceuticals, pesticides, and fungicides. See also CARBAMATES.

Fire Potential:
GRADES: Technical; NF.
Reactivities and Incompatibilities:
This intermediate /N-carbomethoxymethylimino phosphoryl chloride/ (or its ethyl homologue), produced during prepn of phosphoryl dichloride isocyanate from interaction of phosphorus pentachloride & methyl (or ethyl) carbamate, is unstable. Its decomposition to the required product may be violent or explosive unless moderated by the presence of a halogenated solvent.
Incompatibilities: alkalies, acids, antipyrine, chloral hydrate, camphor, menthol, salol, or thymol.
Hot aqueous acids or alkalies decompose urethane to ethanol, carbon dioxide, and ammonia.
Reacts with phosphorous pentachloride to form and explosive product.
Other Preventative Measures:
PRECAUTIONS FOR "CARCINOGENS": Smoking, drinking, eating, storage of food or of food & beverage containers or utensils, & the application of cosmetics should be prohibited in any laboratory. All personnel should remove gloves, if worn, after completion of procedures in which carcinogens have been used. They should ... wash ... hands, preferably using dispensers of liq detergent, & rinse ... thoroughly. Consideration should be given to appropriate methods for cleaning the skin, depending on nature of the contaminant. No standard procedure can be recommended, but the use of organic solvents should be avoided. Safety pipettes should be used for all pipetting. /Chemical Carcinogens/
PRECAUTIONS FOR "CARCINOGENS": In animal laboratory, personnel should remove their outdoor clothes & wear protective suits (preferably disposable, one-piece & close-fitting at ankles & wrists), gloves, hair covering & overshoes. ... clothing should be changed daily but ... discarded immediately if obvious contamination occurs ... /also,/ workers should shower immediately. In chemical laboratory, gloves & gowns should always be worn ... however, gloves should not be assumed to provide full protection. Carefully fitted masks or respirators may be necessary when working with particulates or gases, & disposable plastic aprons might provide addnl protection. If gowns are of distinctive color, this is a reminder that they should not be worn outside of lab. /Chemical Carcinogens/
PRECAUTIONS FOR "CARCINOGENS": ... Operations connected with synth & purification ... should be carried out under well-ventilated hood. Analytical procedures ... should be carried out with care & vapors evolved during ... procedures should be removed. ... Expert advice should be obtained before existing fume cupboards are used ... & when new fume cupboards are installed. It is desirable that there be means for decreasing the rate of air extraction, so that carcinogenic powders can be handled without ... powder being blown around the hood. Glove boxes should be kept under negative air pressure. Air changes should be adequate, so that concn of vapors of volatile carcinogens will not occur. /Chemical Carcinogens/
PRECAUTIONS FOR "CARCINOGENS": Vertical laminar-flow biological safety cabinets may be used for containment of in vitro procedures ... provided that the exhaust air flow is sufficient to provide an inward air flow at the face opening of the cabinet, & contaminated air plenums that are under positive pressure are leak-tight. Horizontal laminar-flow hoods or safety cabinets, where filtered air is blown across the working area towards the operator, should never be used ... Each cabinet or fume cupboard to be used ... should be tested before work is begun (eg, with fume bomb) & label fixed to it, giving date of test & avg air-flow measured. This test should be repeated periodically & after any structural changes. /Chemical Carcinogens/
PRECAUTIONS FOR "CARCINOGENS": Principles that apply to chem or biochem lab also apply to microbiological & cell-culture labs ... Special consideration should be given to route of admin. ... Safest method of administering volatile carcinogen is by injection of a soln. Admin by topical application, gavage, or intratracheal instillation should be performed under hood. If chem will be exhaled, animals should be kept under hood during this period. Inhalation exposure requires special equipment. ... Unless specifically required, routes of admin other than in the diet should be used. Mixing of carcinogen in diet should be carried out in sealed mixers under fume hood, from which the exhaust is fitted with an efficient particulate filter. Techniques for cleaning mixer & hood should be devised before expt begun. When mixing diets, special protective clothing &, possibly, respirators may be required. /Chemical Carcinogens/
PRECAUTIONS FOR "CARCINOGENS": When ... admin in diet or applied to skin, animals should be kept in cages with solid bottoms & sides & fitted with a filter top. When volatile carcinogens are given, filter tops should not be used. Cages which have been used to house animals that received carcinogens should be decontaminated. Cage-cleaning facilities should be installed in area in which carcinogens are being used, to avoid moving of ... contaminated /cages/. It is difficult to ensure that cages are decontaminated, & monitoring methods are necessary. Situations may exist in which the use of disposable cages should be recommended, depending on type & amt of carcinogen & efficiency with which it can be removed. /Chemical Carcinogens/
PRECAUTIONS FOR "CARCINOGENS": To eliminate risk that ... contamination in lab could build up during conduct of expt, periodic checks should be carried out on lab atmospheres, surfaces, such as walls, floors & benches, & ... interior of fume hoods & airducts. As well as regular monitoring, check must be carried out after cleaning-up of spillage. Sensitive methods are required when testing lab atmospheres. ... Methods ... should ... where possible, be simple & sensitive. /Chemical Carcinogens/
PRECAUTIONS FOR "CARCINOGENS": Rooms in which obvious contamination has occurred, such as spillage, should be decontaminated by lab personnel engaged in expt. Design of expt should ... avoid contamination of permanent equipment. ... Procedures should ensure that maintenance workers are not exposed to carcinogens. ... Particular care should be taken to avoid contamination of drains or ventilation ducts. In cleaning labs, procedures should be used which do not produce aerosols or dispersal of dust, ie, wet mop or vacuum cleaner equipped with high-efficiency particulate filter on exhaust, which are avail commercially, should be used. Sweeping, brushing & use of dry dusters or mops should be prohibited. Grossly contaminated cleaning materials should not be re-used ... If gowns or towels are contaminated, they should not be sent to laundry, but ... decontaminated or burnt, to avoid any hazard to laundry personnel. /Chemical Carcinogens/
PRECAUTIONS FOR "CARCINOGENS": Doors leading into areas where carcinogens are used ... should be marked distinctively with appropriate labels. Access ... limited to persons involved in expt. ... A prominently displayed notice should give the name of the Scientific Investigator or other person who can advise in an emergency & who can inform others (such as firemen) on the handling of carcinogenic substances. /Chemical Carcinogens/
SRP: Contaminated protective clothing should be segregated in such a manner so that there is no direct personal contact by personnel who handle, dispose, or clean the clothing. Quality assurance to ascertain the completeness of the cleaning procedures should be implemented before the decontaminated protective clothing is returned for reuse by the workers.
SRP: Local exhaust ventilation should be applied wherever there is an incidence of point source emissions or dispersion of regulated contaminants in the work area. Ventilation control of the contaminant as close to its point of generation is both the most economical and safest method to minimize personnel exposure to airborne contaminants.
Octanol/Water Partition Coefficient:
log Kow = -0.15
NTP 10th Report on Carcinogens. IARC Cancer Review: Group 2B IMEMDT    IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man . 7 ,1987,p. 56.(World Health Organization, Internation Agency for Research on Cancer,Lyon, France.: ) (Single copies can be ordered from WHO Publications Centre U.S.A., 49 Sheridan Avenue, Albany, NY 12210) ; Animal Sufficient Evidence IMEMDT    IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man . 7 ,1974,p. 111.(World Health Organization, Internation Agency for Research on Cancer,Lyon, France.: ) (Single copies can be ordered from WHO Publications Centre U.S.A., 49 Sheridan Avenue, Albany, NY 12210) . Community Right-To-Know List. Reported in EPA TSCA Inventory. EPA Genetic Toxicology Program.
Disposal Methods:
Generators of waste (equal to or greater than 100 kg/mo) containing this contaminant, EPA hazardous waste number U238, must conform with USEPA regulations in storage, transportation, treatment and disposal of waste.
PRECAUTIONS FOR "CARCINOGENS": There is no universal method of disposal that has been proved satisfactory for all carcinogenic compounds & specific methods of chem destruction ... published have not been tested on all kinds of carcinogen-containing waste. ... Summary of avail methods & recommendations ... /given/ must be treated as guide only. /Chemical Carcinogens/
PRECAUTIONS FOR "CARCINOGENS": ... Incineration may be only feasible method for disposal of contaminated laboratory waste from biological expt. However, not all incinerators are suitable for this purpose. The most efficient type ... is probably the gas-fired type, in which a first-stage combustion with a less than stoichiometric air:fuel ratio is followed by a second stage with excess air. Some ... are designed to accept ... aqueous & organic-solvent solutions, otherwise it is necessary ... to absorb soln onto suitable combustible material, such as sawdust. Alternatively, chem destruction may be used, esp when small quantities ... are to be destroyed in laboratory. /Chemical Carcinogens/
PRECAUTIONS FOR "CARCINOGENS": HEPA (high-efficiency particulate arrestor) filters ... can be disposed of by incineration. For spent charcoal filters, the adsorbed material can be stripped off at high temp & carcinogenic wastes generated by this treatment conducted to & burned in an incinerator. ... LIQUID WASTE: ... Disposal should be carried out by incineration at temp that ... ensure complete combustion. SOLID WASTE: Carcasses of lab animals, cage litter & misc solid wastes ... should be disposed of by incineration at temp high enough to ensure destruction of chem carcinogens or their metabolites. /Chemical Carcinogens/
PRECAUTIONS FOR "CARCINOGENS": ... Small quantities of ... some carcinogens can be destroyed using chem reactions ... but no general rules can be given. ... As a general technique ... treatment with sodium dichromate in strong sulfuric acid can be used. The time necessary for destruction ... is seldom known ... but 1-2 days is generally considered sufficient when freshly prepd reagent is used. ... Carcinogens that are easily oxidizable can be destroyed with milder oxidative agents, such as saturated soln of potassium permanganate in acetone, which appears to be a suitable agent for destruction of hydrazines or of compounds containing isolated carbon-carbon double bonds. Concn or 50% aqueous sodium hypochlorite can also be used as an oxidizing agent. /Chemical Carcinogens/
PRECAUTIONS FOR "CARCINOGENS": Carcinogens that are alkylating, arylating or acylating agents per se can be destroyed by reaction with appropriate nucleophiles, such as water, hydroxyl ions, ammonia, thiols & thiosulfate. The reactivity of various alkylating agents varies greatly ... & is also influenced by sol of agent in the reaction medium. To facilitate the complete reaction, it is suggested that the agents be dissolved in ethanol or similar solvents. ... No method should be applied ... until it has been thoroughly tested for its effectiveness & safety on material to be inactivated. For example, in case of destruction of alkylating agents, it is possible to detect residual compounds by reaction with 4(4-nitrobenzyl)-pyridine. /Chemical Carcinogens/
A good candidate for rotary kiln incineration at a temperature range of 820 to 1,600 deg C and residence times of seconds for liquids and gases, and hours for solids. A good candidate for fluidized bed incineration at a temperature range of 450 to 980 deg C and residence times of seconds for liquids and gases, and longer for solids.
The following wastewater treatment technologies have been investigated for urethane: Biological treatment.
These compounds are all hydrolyzed using 5 M sodium hydroxide solution, although the reaction times vary. Methyl carbamate is hydrolyzed to methanol and carbamic acid and urethane /ethyl carbamate/ is hydrolyzed to ethanol and carbamic acid. ... Carbamic acid decomposes to carbon dioxide and ammonia ... In all cases destruction is greater than 99% and good accountances are obtained for the products ... .
Use and Manufacturing
Use and Manufacturing:
Methods of Manufacturing

By heating ethanol & urea nitrate at 120-130 deg C; by action of ammonia on ethyl carbonate or ethyl chloroformate.
Prepared by the reaction of carbamic acid with ethyl alcohol.
... Commercial production is probably the reaction of ethyl chlorocarbonate (made from ethanol and phosgene) with ammonia.
U.S. Production

(1972) 4.5X10+7 G (EST)
(1975) GREATER THAN 4.54X10+5 G (EST)
Molten urethan is good solvent for various organic materials, prepn & modification of amino resins, as solubilizer & co-solvent for pesticides, fumigants.
Biomedical Effects and Toxicity
Pharmacological Action:
- Ultrashort-acting anesthetics that are used for induction. Loss of consciousness is rapid and induction is pleasant, but there is no muscle relaxation and reflexes frequently are not reduced adequately. Repeated administration results in accumulation and prolongs the recovery time. Since these agents have little if any analgesic activity, they are seldom used alone except in brief minor procedures. (From AMA Drug Evaluations Annual, 1994, p174)
- Substances that inhibit or prevent the proliferation of NEOPLASMS.
- Substances that increase the risk of NEOPLASMS in humans or animals. Both genotoxic chemicals, which affect DNA directly, and nongenotoxic chemicals, which induce neoplasms by other mechanism, are included.
Therapeutic Uses:
Anesthetics, Intravenous; Antineoplastic Agents; Carcinogens
/It was/ ... reported in 1968 that urethane had found use in human medicine as an anti-neoplastic agent & formerly was used as a hypnotic, an adjunct to sulfonamide therapy, a component (with quinine) of sclerosing soln for varicose veins, & as a topical bacteriocide.
A more recent source states that large doses of urethane produce bone marrow depression, & that for a time it was used in treatment of chronic leukemia & multiple myeloma. No evidence was found that urethane presently finds use in USA in human medicine.
Medication (vet): reported ... exposures of urethane incl its infrequent use as a hypnotic & its more frequent use as an anesthetic for lab animals.
Medication (vet): has occasionally been used with other drugs, since it not only augments their action, but increases their aq solubility. Wide margin of safety in fish anesthesia, but not popular since it may be carcinogenic to user.
A combination of urethane (95.2 g) & chloralose (9.25 g) in 150 mL normal saline has been used iv (1 mg/kg) for anesthesia in the dog. Urethane is not used clincially because there are safer anesthetics available.
Anti-neoplastic agent; hypnotic; as adjunct to sulfonamide therapy; as component (with quinine) of sclerosing soln for varicose veins, & as topical bactericide. /Former uses/
Biomedical Effects and Toxicity:
The distribution of radiolabelled urethane administered in water or ethanolic solution, was compared in mice by whole-body autoradiography. Two fasted male A/JAX mice were administered 6 uCi (ethyl-1-(14)C)urethane by oral intubation. One mouse received urethane in 1 mL of an aqueous solution, the other in a 12% ethanol solution. One hour after treatment, the mice were frozen and processed for whole body autoradiography. When urethane was administered in water, the radioactivity localized in the salivary, seromucous, and Harderian glands, medullary bone, liver, bile, and epithelia of the stomach and intestine. Lower levels were seen in brown fat, and in the thymus and esophagus. When urethane was administered in ethanol, localization of urethane at each of these sites was almost completely inhibited; high concentrations were still found in the lumen of the stomach and intestine. No evidence was found of transesterification at pH 1.5 in 12% ethanol. [Waddell WJ et al; Food Chem Toxicol 25 (7): 527-31 (1987)] PubMed Abstract
In an attempt to understand route of administration dependency, (3)H-benzo(a)pyrene, (14)C-urethane and (14)C-acrylamide were administered as single doses orally or topically to male Sencar mice. Distribution in skin, stomach, liver, and lung was determined for time periods up to 48 hr. The binding of these compounds to DNA, RNA, and protein in these tissues was determined 6 and 48 hr after administration. For all three compounds, high concentrations were found in the skin following topical application, but very little material reached this target organ following oral administration. The internal organs generally contained more material after oral administration compared to topical application, whereas the opposite was true for the skin. Differences in distribution to the skin and binding to macromolecules following oral or topical administration cannot explain the greater tumorigenicity of urethane and acrylamide after oral administration in the Sencar mouse. [Carlson GP et al; Environ Health Perspect 68: 53-60 (1986)] PubMed Abstract
In mice, urethane is active by transplacental route & is passed to offspring in milk.
After oral administration to rats and mice, /carbamic acid, ethyl ester/ is completely absorbed from the GI tract and rapidly distributed throughout the body. ...Mice eliminated /carbamic acid, ethyl ester/ as /carbon dioxide/ more rapidly than rats.
The extent and persistence of DNA damage and repair were investigated in mouse spermatogenic cells exposed in vivo to urethane (ethyl carbamate, EC). Adult male mice exposed to [3H]EC at 10-1,000 mg/kg were sacrificed 12 hr later. EC/metabolite binding to liver and testicular DNA and to sperm heads from the vasa deferentia was measured. Other male mice were exposed to EC at 50-750 mg/kg, and unscheduled DNA synthesis (UDS) induction was investigated in early spermatid stages. Similar experiments were conducted with vinyl carbamate (VC; putative EC metabolite) at 10-75 mg/kg. [3H]EC bound to liver and testicular DNA and to whole sperm heads. Testicular DNA binding increased linearly with dose, although binding was at least 2 orders of magnitude lower than with liver DNA. Sperm head binding also increased linearly with dose. Dose response studies with the UDS assay showed that EC and VC induced a small but significant increase of the UDS response in early spermatid stages. However, the induced UDS responses were quite variable and did not consistently increase with the administered dose. To determine the time kinetics of UDS induction, [3H]dThd was injected at various times after treatment with 500 mg/kg of EC or 60 mg/kg of VC. A slight but significant UDS increase was observed 4 hr after treatment with EC but not with VC. [Sotomayor RE et al; Environ Mol Mutagen 24 (1): 68-74 (1994)] PubMed Abstract
Adult animals excrete or degrade more than 90% of orally administered urethane within 24 hours but newborn animals are less able to metabolize it.
Environmental Fate and Exposure Potential
Environmental Fate/Exposure Summary:
The rate constant for the vapor-phase reaction of ethyl carbamate with photochemically-produced hydroxyl radicals has been estimated as 7.4X10-12 cu cm/molecule-sec at 25 deg C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 17 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). Hydrolysis if not expected to be an important fate process since carbamates tend to hydrolyze slowly under environmental conditions. A base-catalyzed second-order hydrolysis rate constant of 2.6X10-4 L/mole-sec(SRC) was estimated using a structure estimation method; this corresponds to half-lives of 3,300 and 330 years at pH values of 7 and 8, respectively(2). A neutral hydrolysis rate constant of 290 nm and therefore is not expected to be susceptible to direct photolysis by sunlight(SRC).
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