| 单词 | acetaldehyde | |||
| 释义 | acetaldehydeac·et·al·de·hydeA0050000 (ăs′ĭ-tăl′də-hīd′)acetaldehyde(ˌæsɪˈtældɪˌhaɪd)ac•et•al•de•hyde(ˌæs ɪˈtæl dəˌhaɪd)n. ac·et·al·de·hyde(ăs′ĭ-tăl′də-hīd′)
acetaldehydeacetaldehyde(ăs'ĭtăl`dəhīd) orethanal(ĕth`ənăl'), CH3CHO, colorless liquid aldehydealdehyde[alcohol + New Lat. dehydrogenatus=dehydrogenated], any of a class of organic compounds that contain the carbonyl group, , and in which the carbonyl group is bonded to at least one hydrogen; the general formula for an aldehyde is RCHO, where R is hydrogen ..... Click the link for more information. , sometimes simply called aldehyde. It melts at −123°C;, boils at 20.8°C;, and is soluble in water and ethanol. It is formed by the partial oxidation of ethanol; oxidation of acetaldehyde forms acetic acid. Acetaldehyde is made commercially by the oxidation of ethylene with a palladium catalyst (see Wacker processWacker process, an industrial process for the manufacture of ethanol by oxidizing ethene. For example, bubbling ethylene and oxygen when treated by an acidified water solution of palladium and cupric chlorides yield acetaldehyde; reaction is catalyzed by PdCl2 ..... Click the link for more information. ). It is used as a reducing agent (e.g., for silvering mirrors), in the manufacture of synthetic resins and dyestuffs, and as a preservative. When treated with a small amount of sulfuric acid it forms paraldehyde, (CH3CHO)3, a trimer, which is used as a hypnotic drug. Acetaldehydeacetic aldehyde, CH3CHO, an organic compound; a colorless liquid with a sharp odor. Its boiling point is 20.8°C; its melting point, - 124°C. Its density is 783 kg/m3, and it is miscible in all proportions with water, alcohol, and ether. Acetaldehyde possesses all the properties characteristic of the aldehydes. In the presence of mineral acids it polymerizes into liquid trimeric paraldehyde (CH3CHO)3 and the crystalline tetrameric metaldehyde (CH3CHO)4. When both polymers are heated in the presence of sulfuric acid, acetaldehyde is liberated. One of the long-known, basic methods for the preparation of acetaldehyde consists in combining water with acetylene in the presence of mercuric salts at a temperature of about 95°C (Kucherov’s reaction):
Because of the high cost and toxicity of mercury, another method for the direct catalytic hydration of acetylene has been worked out. A variant of indirect hydration is also possible; it consists in combining alcohol with acetylene in the presence of solid KOH, followed by saponification of the vinyl ether:
Acetaldehyde is also produced from ethyl alcohol by catalytic dehydrogenation at approximately 400°C. When acted upon by aluminum alkoxides, the acetaldehyde is transformed into ethylacetate (Tishchenko’s reaction):
This method has industrial significance. The oxidation of acetaldehyde by atmospheric oxygen over a catalyst is an industrial method for obtaining acetic anhydride. Acetaldehyde participates easily in aldol condensation: 2CH3CHO → CH3—CH(OH)—CH2—CHO Acetaldehyde is used in huge quantities in the production of acetic acid and acetic anhydride, in the preparation of various pharmaceuticals, and so on. acetaldehyde[‚as·əd′al·də‚hīd]acetaldehydeacetaldehydeacetaldehyde[as″et-al´de-hīd]ac·et·al·de·hyde(as-e-tal'dĕ-hīd),acetaldehyde(ăs′ĭ-tăl′də-hīd′)acetaldehydeThe major metabolic product of ethanol, which is generated by ethanol dehydrogenase and subsequently metabolised to acetate by aldehyde dehydrogenase. It is responsible for alcohol’s toxic effects.It is postulated that the liver injury induced by ethanol is due to tissue responses to acetaldehyde, including acetaldehyde-induced fibrogenesis, acetaldehyde-induced lipid peroxidation enzyme inhibition, and formation of antibodies against acetaldehyde adduct proteins—e.g., serum albumin, hemoglobin, and cytokskeletal proteins, including tubulin. Ref range < 0.02 mg/dL. Method Gas chromatography. acetaldehydeToxicology The major metabolic product of ethanol, which is generated by ethanol dehydrogenase and subsequently metabolized to acetate by aldehyde dehydrogenase, and responsible for drinking-alcohol's toxic effectsac·et·al·de·hyde(as'ĕ-tal'dĕ-hīd)acetaldehydeA product of the metabolism of large amounts of alcohol. The reaction is catalyzed in the liver by the enzyme alcohol dehydrogenase. The principal cause of the toxic effects of strong drink. Acetaldehyde is a powerful poison, considerably more toxic than alcohol, and is capable of damaging almost any part of the body. Fortunately the body has a range of detoxifying enzymes, aldehyde dehydrogenases, one of which, ALDH2, rapidly break down the acetaldehyde molecule.acetaldehyde
Synonyms for acetaldehyde
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acetaldehyde - a colorless volatile water-soluble liquid aldehyde used chiefly in the manufacture of acetic acid and perfumes and drugs
