acetaldehyde


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acetaldehyde

(ăs'ĭtăl`dəhīd) or

ethanal

(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
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, 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
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). 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.

Acetaldehyde

 

acetic 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]
(organic chemistry)
C2H4O A colorless, flammable liquid used chiefly to manufacture acetic acid.

acetaldehyde

a colourless volatile pungent liquid, miscible with water, used in the manufacture of organic compounds and as a solvent and reducing agent. Formula: CH3CHO
References in periodicals archive ?
The team genetically modified the mice with a mutation that prevented blood stem cells from producing one of these enzymes - ALDH2 - to analyze the damage caused by acetaldehyde.
Also, catalase can participate in the production of acetaldehyde from the ethanol present in the brain.
Analysis of the wines also revealed that the majority of acetaldehyde and pyruvic acid was degraded by O.
Catalase and CYP2E1 are the main pathways; there is evidence that they do indeed play an important role in ethanol oxidation to acetaldehyde in the brain [91].
It has been assumed in early case reports that metronidazole caused a similar interaction with alcohol and raised acetaldehyde levels by interfering with aldehyde dehydrogenase.
The amounts of formaldehyde and acetaldehyde were determined by the standard 13-carbonyl compounds (Supelco, CARB 1004 DNPH Mix2).
Acetaldehyde is the key toxic substance in alcohol metabolism.
Culture conditions and biotransformationThe acetaldehyde and benzaldehyde resistant cultures were screened through submerged fermentation after Shukla et al.
7Homann et al7 demonstrated increased salivary acetaldehyde levels even after ingesting moderate amounts of ethanol allowing significant acetaldehyde accumulation in oral tissues during chronic ethanol consumption and may explain some of the cytologic anomalies in the oral mucosa of non-smoker alcoholics.
com)-- The global value of the acetaldehyde market in terms of production is estimated to reach 1.
Freshly cut samples generally had a significant increase in total volatile compounds, with acetaldehyde being most abundant.
When you are drinking excessively, the body cannot break it down quickly enough so the acetaldehyde remains in the body for longer.