Acetaldehyde
Acetaldehyde
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Acetaldehyde

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Acetaldehyde

Acetaldehyde (IUPAC systematic name ethanal) is an organic chemical compound with the formula CH3CH=O. It is a colorless liquid or gas, boiling near room temperature. It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale in industry. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit, and is produced by plants. It is also produced by the partial oxidation of ethanol by the liver enzyme alcohol dehydrogenase and is a contributing cause of hangover after alcohol consumption. Pathways of exposure include air, water, land, or groundwater, as well as drink and smoke. Consumption of disulfiram inhibits acetaldehyde dehydrogenase, the enzyme responsible for the metabolism of acetaldehyde, thereby causing it to build up in the body.

The International Agency for Research on Cancer (IARC) has listed acetaldehyde as a Group 1 carcinogen. Acetaldehyde is "one of the most frequently found air toxins with cancer risk greater than one in a million".

Acetaldehyde was first observed by the Swedish pharmacist/chemist Carl Wilhelm Scheele (1774); it was then investigated by the French chemists Antoine François, comte de Fourcroy and Louis Nicolas Vauquelin (1800), and the German chemists Johann Wolfgang Döbereiner (1821, 1822, 1832) and Justus von Liebig (1835).

In 1835, Liebig named it "aldehyde", and in the middle of the century the name was altered to "acetaldehyde".

In 2013, global production was about 438,000 tonnes. Before 1962, ethanol and acetylene were the major sources of acetaldehyde. Since then, ethylene is the dominant feedstock.

The main method of production is the oxidation of ethene by the Wacker process, which involves oxidation of ethene using a homogeneous palladium/copper catalyst system:

In the 1970s, the world capacity of the Wacker-Hoechst direct oxidation process exceeded two million tonnes annually.

Smaller quantities can be prepared by the partial oxidation of ethanol in an exothermic reaction. This process typically is conducted over a silver catalyst at about 500–650 °C (950–1,200 °F).

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