释义 |
ethylene
eth·yl·ene E0231000 (ĕth′ə-lēn′)n. A colorless flammable gas, C2H4, derived from natural gas and petroleum and also occurring as a natural plant hormone, used as a source of many organic compounds, in welding and cutting metals, to ripen citrus fruits, and as an anesthetic. Also called ethene. eth′yl·e′nic (-ə-lē′nĭk, -lĕn′ĭk) adj.ethylene (ˈɛθɪˌliːn) n (Elements & Compounds) a colourless flammable gaseous alkene with a sweet odour, obtained from petroleum and natural gas and used in the manufacture of polythene and many other chemicals. Formula: CH2:CH2. Also called: ethene ethylenic adjeth•yl•ene (ˈɛθ əˌlin) n. a colorless, flammable gas, C2H4, used as an agent in the synthesis of organic compounds, in enhancing the color of citrus fruits, and in medicine chiefly as an inhalation anesthetic. [1850–55] eth`yl•e′nic (-ˈli nɪk, -ˈlɛn ɪk) adj. eth·yl·ene (ĕth′ə-lēn′) A colorless, flammable gas, C2H4, obtained from petroleum and natural gas. It is used as a fuel, in making plastics, and in ripening and coloring fruits. Also called ethene.ThesaurusNoun | 1. | ethylene - a flammable colorless gaseous alkene; obtained from petroleum and natural gas and used in manufacturing many other chemicals; sometimes used as an anestheticethenealkene, olefin, olefine - any unsaturated aliphatic hydrocarbonTCE, trichloroethane, trichloroethylene - a heavy colorless highly toxic liquid used as a solvent to clean electronic components and for dry cleaning and as a fumigant; causes cancer and liver and lung damagegas - a fluid in the gaseous state having neither independent shape nor volume and being able to expand indefinitely | Translationsethylene
ethylene (ĕth`əlēn') or ethene (ĕth`ēn), H2C=CH2, a gaseous unsaturated hydrocarbon. It is the simplest alkenealkene , any of a group of aliphatic hydrocarbons whose molecules contain one or more carbon-carbon double bonds (see chemical bond). Alkenes with only one double bond have the general formula CnH2n. ..... Click the link for more information. . Ethylene is colorless, has a faint odor, and has a slightly sweet taste; it melts at −169.4°C; and boils at −103.8°C;. Because of the presence of the double bond in its molecule, ethylene is very reactive. It burns in air with a luminous flame and forms explosive mixtures with pure oxygen. It combines directly with the halogens, e.g., with chlorine to form 1,2-dichloroethane. With hydrogen it forms ethane. Ethylene may be prepared by the dehydration of ethanol with sulfuric acid at about 180°C;. It is prepared commercially from natural gas and petroleum, e.g., by cracking and fractional distillation. Ethylene has many uses. It is important in the synthesis of many chemicals that are used to produce plastics and other petrochemical products. It is used in making polyethylene and saran, in the manufacture of ethanol, ethylene oxide, and ethylene glycol, and as an anesthetic. Ethylene was called olefiant gas by early chemists.Ethylene (also ethene), H2C═CH2, an unsaturated hydrocarbon; the first member of the homologous series of olefins (alkenes). Ethylene takes the form of a colorless gas with a weak ethereal odor. It has a melting point of –169.5°C, a boiling point of –103.8°C, and a density of 0.570 g/cm3 at –103.8°C. Virtually insoluble in water, it is poorly soluble in ethyl alcohol; it dissolves better in ether and acetone. Ethylene has a flash point of 540°C, and it burns with a slightly smoky flame. Mixtures of ethylene and air become explosive when the concentration of ethylene is 3–34 percent by volume. Ethylene is highly reactive. Its most characteristic reaction is addition to the carbon-carbon double bond. For example, the catalytic hydrogenation of ethylene yields ethane according to the reaction H2C═CH2 + H2 → H3C—CH3 Similarly, the chlorination of ethylene produces dichloroethane, as described by the equation H2C═CH2 + C12 → C1H2C—CH2Cl Hypochlorination (the addition of hypochlorous acid) yields ethylene chlorohydrin according to the reaction H2C═CH2 + HOCl → HOH2C—CH2Cl Many reactions of ethylene serve as a basis for industrial methods of producing important chemicals. For example, ethyl alcohol is produced by either the single-step or two-step hydration of ethylene (see), and ethylene oxide and acetaldehyde are produced by the oxidation of ethylene. The alkylation of benzene by ethylene gives ethylbenzene (seeFRIEDEL-CRAFTS REACTION), polymerization gives polyethylene (in the presence of Ziegler-Natta catalysts, for example), and oxidative chlorination yields vinylchloride. Vinyl acetate is produced by reacting ethylene with acetic acid; ethyl chloride, by adding hydrogen chloride; and mustard gas, by reacting ethylene with sulfur chlorides. The principal industrial method for producing ethylene is the thermal cracking (at 700°-850°C) of liquid petroleum distillates and lower alkanes—mainly ethane and propane (seePETROLEUM REFINING GASES). The separation and purification of ethylene are performed by fractional distillation, fractional absorption, and deep cooling. In the laboratory, ethylene is prepared by the dehydration of ethyl alcohol; this process may be accomplished by various methods, including heating the alcohol with either sulfuric or phosphoric acid. Ethylene in living organisms. Ethylene is formed in very small amounts in plant and animal tissues as a metabolic intermediate. In the fruits, flowers, leaves, stems, and roots of plants, it interferes with the activity and biosynthesis of a class of plant hormones known as auxins, which similarly inhibit the activity and biosynthesis of ethylene. When ethylene is predominant, it slows the growth of plants and accelerates the aging, ripening, and falling of fruits and the shedding of flowers (or their corollas), pericarp, and leaves; when auxins predominate, their effects include inhibition of the aging, ripening, and falling of fruit. The biosynthetic pathways of ethylene and its metabolism in plant tissues have not been definitively established. Ethylene is used to accelerate the ripening of fruits (including tomatoes, melons, oranges, mandarins, lemons, and bananas), defoliate plants, reduce the falling of fruits before the harvest, and reduce the strength of the attachment of the fruit to the mother plant (thus facilitating mechanized harvesting). In high concentrations, ethylene has an anesthetic effect on humans and animals. REFERENCESJensen, E. “Etilen i poliatsetileny.” Biokhimiia rastenii. Moscow, 1968. (Translated from English.) “Stimuliatsiia i tormozhenie fiziologicheskikh protsessov u rastenii.” In the collection Istoriia i sovremennoe sostoianoe fiziologii rastenii. Moscow, 1967.IU. V. RAKITIN ethylene[′eth·ə‚lēn] (organic chemistry) C2H4 A colorless, flammable gas, boiling at -102.7°C; used as an agricultural chemical, in medicine, and for the manufacture of organic chemicals and polyethylene. Also known as ethene; olefiant gas. ethylene a colourless flammable gaseous alkene with a sweet odour, obtained from petroleum and natural gas and used in the manufacture of polythene and many other chemicals. Formula: CH2:CH2 ethylene
ethylene [eth´ĭ-lēn] a colorless, highly flammable gas with a slightly sweet taste and odor, used as an inhalation anesthetic to induce anesthesia" >general anesthesia.ethylene glycol a solvent with a sweet, acrid taste, used as an antifreeze. Acute poisoning by ingestion can result in central nervous system depression, vomiting, hypotension, coma, convulsions, renal damage, and death. While damage is thought to be due to the formed oxalic acid, ethanol is a good treatment because it competitively inhibits alcohol dehydrogenase. The unaltered ethylene glycol is then excreted in the urine.ethylene oxide a gaseous, flammable alkylating agent with a broad spectrum of activity, capable of killing both spores and viruses; it must be mixed with CO2 or fluorocarbons because it is explosive above 3 per cent. It is used in hospitals, surgery, dentistry, and the pharmaceutical and other industries for disinfecting and sterilizing instruments and equipment that would be destroyed by heat or would be adversely affected by immersion in water or other media. Its optimal germicidal effect occurs after a 3-hour exposure at 30°C. Ethylene oxide is toxic because it alkylates tissue constituents; it is carcinogenic and may produce adverse reproductive effects. Inhalation may cause nausea, vomiting, and neurological disorders, and severe exposure may be fatal. Before items exposed to ethylene oxide can be used they must be aired for 5 days at room temperature or for 8 hours at 120° C to remove any trace of the gas. This is also true for articles of clothing, such as gloves and shoes, that have been exposed, because chemical burns can occur when the contaminated clothing comes in contact with the skin.eth·yl·ene (eth'il-ēn), An explosive constituent of ordinary illuminating gas; hastens ripening of fruit.ethylene (ĕth′ə-lēn′)n. A colorless flammable gas, C2H4, derived from natural gas and petroleum and also occurring as a natural plant hormone, used as a source of many organic compounds, in welding and cutting metals, to ripen citrus fruits, and as an anesthetic. Also called ethene. eth′yl·e′nic (-ə-lē′nĭk, -lĕn′ĭk) adj.ethylene or ethene a simple hydrocarbon with the formula CH2=CH2 that can act as a PLANT HORMONE even when present in very low concentrations (down to 1 ppm). Ethylene inhibits elongation in most growing tissues and promotes leaf ABSCISSION and fruit ripening in some plants. Plant cells produce ethylene from the amino acid METHIONINE. A ripe banana or tomato in a bowl of unripe ones will speed up the ripening process by giving off ethylene.eth·yl·ene (eth'il-ēn) An explosive constituent of ordinary illuminating gas. ethylene Related to ethylene: ethylene glycolSynonyms for ethylenenoun a flammable colorless gaseous alkeneSynonymsRelated Words- alkene
- olefin
- olefine
- TCE
- trichloroethane
- trichloroethylene
- gas
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