| 单词 | cyanide | ||||||
| 释义 | cyanidecy·a·nideC0831800 (sī′ə-nīd′)cyanide(ˈsaɪəˌnaɪd) orcyanidcy•a•nide(ˈsaɪ əˌnaɪd, -nɪd)n., v. -nid•ed, -nid•ing. n. cy·a·nide(sī′ə-nīd′)
cyanide(ˈsaiənaid) nouncyanidecyanide(sī`ənīd'), chemical compound containing the cyano groupcyano group, in chemistry, functional group that consists of a carbon atom joined to a nitrogen atom by a triple bond; it can be joined to an atom or another group by a single bond to the carbon atom. When a cyano group is joined to hydrogen, it forms hydrogen cyanide. ..... Click the link for more information. , -CN. Cyanides are salts or esters of hydrogen cyanidehydrogen cyanide, HCN, colorless, volatile, and extremely poisonous chemical compound whose vapors have a bitter almond odor. It melts at −14°C; and boils at 26°C;. It is miscible in all proportions with water or ethanol and is soluble in ether. ..... Click the link for more information. (hydrocyanic acid, HCN) formed by replacing the hydrogen with a metal (e.g., sodium or potassium) or a radical (e.g., ammonium or ethyl). The most common and widely used cyanides are those of sodium and potassium; they are often referred to simply as "cyanide." Both are white, crystalline, chemically active compounds. They are used as insecticides, in making pigments, in metallurgy (e.g., electroplating and case hardening), and in refining gold and silver by the cyanide processcyanide process or cyanidation, method for extracting gold from its ore. The ore is first finely ground and may be concentrated by flotation; if it contains certain impurities, it may be roasted. ..... Click the link for more information. . Organic cyanides are called nitriles. The ethyl ester of hydrogen cyanide (CH3CH2CN) is called variously ethyl cyanide, propionitrile, propane nitrile, nitrilopropane, and cyanoethane; propane nitrile is the approved name in the nomenclature system for organic chemistry adopted by the International Union of Pure and Applied Chemistry (IUPAC). Most cyanides are deadly poisons that cause respiratory failure. Symptoms of cyanide poisoning include an odor of bitter almond on the breath, dizziness, convulsions, collapse, and, often, froth on the mouth. In case of cyanide poisoning a doctor should be summoned immediately. If the poison was swallowed, vomiting should be induced. Artificial respiration should be used if needed. Cyanidea salt of hydrocyanic acid. The cyanide salts of the alkali metals MCN and the alkaline-earth metals M(CN)2, where M is a metal, are thermally stable but are hydrolyzed in aqueous solutions. The cyanides of the heavy metals are thermally unstable and, with the exception of Hg(CN)2, are insoluble in water. The oxidation of cyanides leads to the formation of cyanates; for example, 2KCN + O2 → 2KOCN. Many metals upon the action of an excess of potassium cyanide or sodium cyanide yield complexes. This proves useful in the extraction of gold and silver from ores (cyanidation, cyanide process): 4NaCN + 2Au + ½O2 + H2O → 2Na[ Au(CN)2] + 2NaOH Gold and silver are separated from solution by electrodeposition or by the action of metallic zinc. Solutions of the cyanide complexes of gold, silver, zinc, and other metals are used in electroplating technology for the production of coatings. Cyanides are also used in organic synthesis, for example, in the production of nitriles, and as catalysts (in benzoin condensation). Cyanides are extremely toxic. (For information on the effect of cyanides on the organism and on safety measures when handling them, seeHYDROCYANIC ACID.) REFERENCESBobkov, S. S., and S. K. Smirnov. Sinil’naia kislota. Moscow, 1970.Zil’berman, E. N. Reaktsii nitrilov. Moscow, 1972. Tomilov, A. P., and S. K. Smirnov. Adipodinitril i geksamet ilendiamin. Moscow, 1974. Williams, H. E. Cyanogen Compounds, 2nd ed. London, 1948. Migrdichian, V. The Chemistry of Organic Cyanogen Compounds. New York, 1947. Methoden der Organischen Chemie (Houben-Weyl), 4th ed., vol. 8. Stuttgart, 1952. S. K. SMIRNOV cyanide[′sī·ə‚nīd]cyanide, cyanidcyanidecyanide[si´ah-nīd]Treatment varies according to the nature of the poison. In the case of swallowed poison like hydrocyanic acid, the poison itself will cause vomiting. If the victim is able to swallow, milk or water may be given. A large dose of hydrocyanic acid will cause almost instant death. If a gas such as hydrogen cyanide has been inhaled, the victim should be taken into open air and given artificial respiration. Sodium thiosulfate and sodium nitrate are used as antidotes to cyanide poisoning. While poisoning may occur following exposure to any substance that releases cyanide ions, it can also occur concurrently if another toxic ion is present (for example, with mercuric cyanide). In such a situation, ironically the symptoms of toxicity may change to those of the second ion when the antidote to cyanide is used. cy·a·nide(sī'an-īd),cyanideA highly reactive compound (CN–) with a high affinity for metal ions (e.g., iron of cytochrome oxidase); in vivo, cyanide usually exists as a salt—e.g., hydrogen cyanide (HCN), potassium cyanide (KCN) and others. HCN is produced by the thermal decomposition of various nitrogen-containing compounds, either natural (e.g., wool and silk) or synthetic (e.g., polyurethane and polyacrylonitrile) It is one of the two principal toxic gases that cause death in fires (the other is carbon monoxide); ambient cyanide levels of > 500 ppm are lethal within 10 minutes.Laboratory The mean cyanide concentration of victims who died in fatal fires in one study was 116 µmol/L, and 22 µmol/L in those who lived; the serum T1⁄2 for HCN is one hour. The plasma lactate levels in those who died was 29 mmol/L; lactate levels correlate well with HCN levels and may serve as a surrogate marker. Management Various agents have been used to treat cyanide poisoning, in particular those that transform haemoglobin to methaemoglobin, which avidly binds cyanide. This manoeuvre is limited by the methaemoglobin’s ferric state (Fe3+), which cannot bind O2, and at levels of > 30% exacerbates the tissue hypoxia caused by the cyanides. cyanideToxicology A reactive ion–CN– with a high affinity for metal ions–eg, iron of cytochrome oxidase; in vivo, cyanide usually exists as a salt–eg, hydrogen cyanide–HCN, KCN, etc Lab Mean cyanide concentration of victims who died in fatal fires in one study was 116 µmol/L, and 22 µmol/L in those who lived; serum T1⁄2 for HCN is 1 hr; plasma lactate levels in those who died was 29 mmol/L; lactate levels correlate well with HCN levels and may serve as a surrogate marker Management Agents used to treat cyanide poisoning, include those that transform Hb to metHb, which avidly binds cyanide; this maneuver is limited by metHb's ferric state–Fe3+, which cannot bind O2, and at > 30% exacerbates tissue hypoxia caused by the cyanidescy·a·nide(sī'ăn-īd)See also: blood agent, hydrogen cyanide, cyanogen chloride cyanideany salt of hydrocyanic acid. Potassium cyanide (KCN) and hydrogen cyanide (HCN) are the commonest examples of cyanides, all of which are extremely poisonous. They combine with cytochrome enzymes (e.g. CYTOCHROME OXIDASE), which transfer hydrogen atoms in CELLULAR RESPIRATION, and thus block the production of energy in the cells.cyanide
Synonyms for cyanide
|
||||||
| 随便看 |
|
英语词典包含2567994条英英释义在线翻译词条，基本涵盖了全部常用单词的英英翻译及用法，是英语学习的有利工具。