Science Fair Project Encyclopedia
It is a highly reactive flammable liquid with a strong fruity smell. It melts at -123.5° C and boils at 21° C.
In the liver, the enzyme alcohol dehydrogenase converts ethanol into acetaldehyde, which is then further converted into the harmless acetic acid by acetaldehyde dehydrogenase. Acetaldehyde is more toxic than alcohol and is responsible for many hangover symptoms. N-acetylcysteine (NAC) is known to assist in processing acetaldehyde in the body and therefore can help to relieve hangover symptoms.
Some persons from far-Eastern descent have a mutation in their acetaldehyde dehydrogenase gene, making this enzyme less effective. In these people, acetaldehyde accumulates after drinking, leading to severe and immediate hangover symptoms. These people are therefore less likely to become alcoholics. The drug antabuse (disulfiram) also prevents the oxidation of acetaldehyde to acetic acid, with the same unpleasant effects for drinkers. It is used in the treatment of certain alcoholics.
The last steps of alcoholic fermentation in bacteria, plants and yeast involves the conversion of pyruvate into acetaldehyde by the enzyme pyruvate decarboxylase , followed by the conversion of acetaldehyde into ethanol. The latter reaction is again catalyzed by alcohol dehydrogenase, now operating in the opposite direction.
In the chemical industry, acetaldehyde is mainly used as an intermediary to produce acetic acid, certain esters, and a number of other chemicals. In 1989, US production stood at 740 million pounds (336,000 t).
When exposed to acetaldehyde vapors, humans develop irritation of the eyes, skin and the respiratory tract. Acetaldehyde is an air pollutant, emitted by cars and certain production facilities. It is also contained in tobacco smoke. It is classified as a probable carcinogen.
Three molecules of acetaldehyde can form the cyclic paraldehyde, and four can form the cyclic acetaldehyde tetramer .
- EPA factsheet about acetaldehyde
- Hal Kibbey: Genetic Influences on Alcohol Drinking and Alcoholism, Indiana University Research and Creative Activity, Vol. 17 no. 3.
- United States Food and Drug Administration (FDA) information for acetaldehyde
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details