Уретан

Описание

Ethyl carbamate occurs as colourless or white columnar crystals or granular powder. It is very soluble in water. With heat, ethyl carbamate undergoes decomposition and emits toxic fumes of carbon monoxide, carbon dioxide, and nitrogen oxides. Ethyl carbamate is used as an intermediate in the synthesis of a number of chemical products, for example, pharmaceuticals, in biochemical research and medicine, and as a solubiliser and co-solvent for pesticides and fumigants. Prior to World War II, ethyl carbamate saw relatively heavy use in the treatment of multiple myeloma before it was found to be toxic, carcinogenic, and largely ineffective. However, due to U.S. FDA regulations, ethyl carbamate has been withdrawn from pharmaceutical use. However, small quantities of ethyl carbamate are also used in laboratories as an anaesthetic for animals.

Химические свойства

Urethane is a colorless, almost odorless crystalline solid or powder.

Вхождение

Urethane (ethyl carbamate) occurs as a natural byproduct in fermented products such as wine, liquors, yogurt, beer, bread, olives, cheeses, and soy sauces. Whereas urethane has a known cancer etiology in experimental animals, no such relationship has yet been proven in humans. Alcohol may act by blocking the metabolism of urethane, and thus exert a protective effect in humans consuming alcoholic beverages.

Использование

The primary use of urethane has been as a chemical intermediate in preparation of amino resins (IARC 1974). The process involves a reaction with formaldehyde to give hydroxymethyl derivatives that are used as cross-linking agents in permanent-press textile treatments designed to impart wash-and-wear properties to fabrics. Urethane isalso used as a solubilizer and co-solvent in the manufacture of pesticides, fumigants, and cosmetics, as an intermediate in the manufacture of pharmaceuticals, and in biochemical research (HSDB 2009). Urethane was formerly used as an active ingredient in drugs prescribed for the treatment of neoplastic diseases, as a sclerosing solution for varicose veins, as a hypnotic, and as a topical bactericide. It is also used in veterinary medicine as an anesthetic (IARC 1974). Urethane is produced naturally during many fermentation processes(Zimmerli and Schlatter 1991).

Определение

A poisonous flammable organic compound, used in medicine, as a solvent, and as an intermediate in the manufacture of polyurethane resins.

Всемирная организация здравоохранения(ВОЗ)

Urethane was formerly used as an antineoplastic agent in the treatment of chronic myeloid leukaemia. It is also a mild hypnotic which has been used as an anaesthetic for veterinary practice. It has been reported to have both a carcinogenic and mutagenic potential. Although urethane continues to be used as an industrial solvent, WHO has no information to suggest that it remains commercially available in pharmaceutical preparations.

Общее описание

Odorless colorless crystals or white powder. Sublimes readily at 217°F and 54 mm Hg. Cooling saline taste.

Реакции воздуха и воды

Water soluble. Aqueous solutions are neutral to litmus .

Профиль реактивности

Urethane is incompatible with alkalis, acids, chloral hydrate, camphor, menthol and thymol. Also incompatible with antipyrine and salol. May react with strong oxidizing agents. Liquefies with benzoic acid, resorcinol and salicylic acid. Reacts with phosphorus pentachloride to form an explosive product .

Опасность

Toxic by ingestion.

Профиль безопасности

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 intermedate in the manufacture of pharmaceuticals, pesticides, and fungicides. See also CARBAMATES.

Возможный контакт

Urethane is used as a chemical intermediate in manufacture of pharmaceuticals; pesticides, and fungicides; in the preparation of amino resins. It may be reacted with formaldehyde to give cross-linking agents which impart wash-and-wear properties to fabrics. It has also been used as a solubilizer and cosolvent in the manufacture of pesticides, fumigants, and cosmetics. It was formerly used in the treatment of leukemia. It occurs when diethylpyrocarbonate, a preservative used in wines, fruit juices, and soft drinks, is added to aqueous solutions.

Канцерогенность

Urethane is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals.

Экологическая судьба

Urethane may be released to the environment in various waste streams. If released to the atmosphere, urethane is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase urethane is degraded in the atmosphere by reaction with photochemically produced hydroxyl radicals with an estimated half-life of 2.2 days. If released to soil, urethane has very high mobility. Volatilization from moist soil surfaces does not occur. Biodegradation of urethane in soil may be important. If released into water, urethane is not adsorbed to suspended solids and sediment in the water column. Volatilization from water surfaces does not occur. The potential for bioconcentration in aquatic organisms is low based on an estimated bioconcentration factor (BCF) of 0.45. Urethane is resistant to hydrolysis under environmental conditions; hydrolysis half-lives of 3300 and 330 years at pH 7 and 8, respectively, were estimated for urethane. Urethane was judged easy to biodegrade in river die-away tests. Other biodegradation studies using activated sludge indicate urethane may biodegrade slowly.

Методы очистки

Urethane is best purified by fractional distillation, but it can be 20 25 1.4144. sublimed at ~103o/~50mm. It has also been recrystallised from *benzene. Its solubilitiy at room temperature is 2g/mL in H2O, 1.25g/mL in EtOH, 1.1g/mL in CHCl3, 0.67g/mL in Et2O and 0.03g/mL in olive oil. It is a suspected human carcinogen.[Beilstein 3 H 22, 3 IV 40.]

Несовместимости

Dust may form explosive mixture with air. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides, gallium, perchlorate.

Утилизация отходов

Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform to EPA regulations governing storage, transportation, treatment, and waste disposal. Controlled incineration (incinerator equipped with a scrubber or thermal unit to reduce nitrogen oxides emissions).