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

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

acetaldehyde

[‚as·əd′al·də‚hīd]

(organic chemistry)

C₂H₄O A colorless, flammable liquid used chiefly to manufacture acetic acid.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

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.

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References in periodicals archive

BMDL10 values were: 56, 0.36, 0.25 and 28mg [kg.sup.-1] of body weight per day were used for acetaldehyde (LACHENMEIER et al., 2009), acrolein (ATSDR, 2007), EC (SCHLATTER et al., 2010) and formaldehyde (MONAKHOVA et al., 2012), respectively, as already mentioned in a previous study (FERREIRA et al.

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The ethanol and acetaldehyde content in grapes with different degrees of rotting, the mortality and ADH and ALDH activity levels of D.

Ecological niche difference associated with varied ethanol tolerance between Drosophila suzukii and Drosophila melanogaster (Diptera: Drosophilidae)

Their ethanol and acetaldehyde production is low at ripening, as displayed in the figures 4A and B.

Astringency reduction using ethanol-associated to the storing under refrigeration at 5[degrees]C promotes physiological and structural alterations in 'Giombo' persimmons

Cells were divided into six groups and seeded at 2 x [10.sup.6] for each group in 10-cm culture dish as follows: two groups were the untreated cells, while the other four groups were induced by acetaldehyde 100 [micro]M for 24 h.

Alpha Mangostin Inhibits the Proliferation and Activation of Acetaldehyde Induced Hepatic Stellate Cells through TGF-[beta] and ERK 1/2 Pathways

One control group (cells untreated with acetaldehyle), an acetaldehyde group (200 [micro]mol/L), and three L-Cys groups with high, medium, and low concentrations of L-Cys (640,160, and 40 [micro]mol/L) were included in the study.

Cellular and Molecular Evidence of Acetaldehyde Elimination and Intracellular Environment Antioxidation by L-Cysteine

Also, catalase can participate in the production of acetaldehyde from the ethanol present in the brain.

Ethanol Intake and Toxicity: In Search of New Treatments/Ingesta de Etanol y Toxicidad: En Busqueda de Nuevos Tratamientos

The formation of polymeric pigments can be accelerated through reactions with acetaldehyde that result via ethyl-linked bridges between anthocyanins and tannins.

Loss of Pinot Noir color and polymeric pigment: measuring the effects of malolactic fermentation and possible mechanisms