Acetaldehyde

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Ethanal Ethenol Tautomerie

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Acetal formation 2

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Production of acetaldehyde

Poly(ethylene terephthalate) - Type II Norrish to acetaldehyde

Acetaldehyde (IUPAC name: ethanal) is an organic compound with the chemical formula C₂H₄O. It is a colorless, flammable liquid with a sharp, pungent odor. Acetaldehyde occurs naturally in various plants, ripe fruits, vegetables, and is also produced by the partial oxidation of ethanol by the liver enzyme alcohol dehydrogenase during the metabolism of alcohol. It is a significant constituent in the global carbon cycle and a central intermediate in the metabolism of sugars and alcohols.

Production

Acetaldehyde is primarily produced by the oxidation of ethylene via the Wacker process, a method that involves the reaction of ethylene with oxygen in the presence of a palladium catalyst. Another method of production involves the hydration of acetylene, a process that was historically significant but has largely been replaced by the Wacker process due to its efficiency and lower costs.

Uses

Acetaldehyde has a wide range of applications in the chemical industry. It is a key intermediate in the synthesis of acetic acid, peracetic acid, ethyl acetate, and various other chemicals. It is also used in the production of perfumes, flavors, and aniline dyes. In addition, acetaldehyde is employed in the manufacture of plastics, paints, and rubber.

Health Effects

Exposure to acetaldehyde can pose several health risks. It is classified as a probable human carcinogen by the International Agency for Research on Cancer (IARC) and is known to cause irritation to the eyes, skin, and respiratory tract. Ingestion or prolonged exposure to high levels of acetaldehyde can lead to serious health issues, including liver damage, central nervous system depression, and an increased risk of cancer. The compound is also implicated in the development of alcohol-related diseases, including alcoholic liver disease and certain forms of cancer, as it is a major metabolite of ethanol in the human body.

Environmental Impact

Acetaldehyde is a volatile organic compound (VOC) that contributes to air pollution and the formation of photochemical smog. It is released into the environment through various industrial processes, as well as from the combustion of fossil fuels and biomass. The compound can also be emitted from certain plants and during the fermentation process in winemaking, brewing, and bread making.

Regulation

Due to its health and environmental impacts, the production, use, and emission of acetaldehyde are regulated in many countries. Regulations aim to minimize human exposure and reduce the release of acetaldehyde into the environment. This includes setting permissible exposure limits in the workplace, controlling emissions from industrial plants, and monitoring its presence in foods and beverages.

See Also

• Ethanol metabolism
• Oxidative stress
• Volatile organic compound