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An acetate is a salt formed by the combination of acetic acid with a base (e.g. Alkali metal, earthy, Transition metal, nonmetallic, or radical base). "Acetate" also describes the conjugate acid or ion (specifically, the negatively charged ion called an anion) typically found in aqueous solution and written with the chemical formula . The neutral molecules formed by the combination of the acetate ion and a positive ion (called a cation) are also commonly called "acetates" (hence, acetate of lead, acetate of aluminium, etc.). The simplest of these is hydrogen acetate (called acetic acid) with corresponding salts, , and the polyatomic ion , or .
Most of the approximately 5 million tonnes of acetic acid produced annually in industry are used in the production of acetates, which usually take the form of polymers. In nature, acetate is the most common building block for biosynthesis.
Although its systematic name is ethanoate (), the common acetate remains the preferred IUPAC name. R-9.1 Trivial and semisystematic names retained for naming organic compounds , A Guide to IUPAC Nomenclature of Organic Compounds, IUPAC Commission on Nomenclature of Organic Chemistry
can be complexed by acetate. Examples of acetate complexes include chromium(II) acetate and basic zinc acetate.
Commercially important acetate salts are aluminium acetate, used in dyeing, ammonium acetate, a precursor to acetamide, and potassium acetate, used as a diuretic. All three salts are colourless and highly soluble in water.Hosea Cheung, Robin S. Tanke, G. Paul Torrence "Acetic acid" in Ullmann's Encyclopedia of Industrial Chemistry Weinheim, Germany: Wiley-VCH, 2005.
Almost half of acetic acid production is consumed in the production of vinyl acetate, precursor to polyvinyl alcohol, which is a component of many . The second largest use of acetic acid is consumed in the production of cellulose acetate. In fact, "acetate" is jargon for cellulose acetate, which is used in the production of fibres or diverse products, e.g. the used in audio record production. Cellulose acetate can be found in many household products. Many industrial are acetates, including methyl acetate, ethyl acetate, isopropyl acetate, and ethylhexyl acetate. Butyl acetate is a fragrance used in food products.
Intraperitoneal injection of sodium acetate (20 or 60 mg per kg body mass) was found to induce headache in sensitized rats, and it has been proposed that acetate resulting from oxidation of ethanol is a major factor in causing . Increased serum acetate levels lead to accumulation of adenosine in many tissues including the brain, and administration of the adenosine receptor antagonist caffeine to rats after ethanol was found to decrease nociceptive behavior. 'Is coffee the real cure for a hangover?' by Bob Holmes, New Scientist, Jan. 15 2011, p. 17.
Acetate has known immunomodulatory properties and can affect the innate Immune system response to pathogenic bacteria such as the respiratory pathogen Haemophilus influenzae.
acetyl-CoA + phosphate → acetyl-phosphate + CoA
acetyl-phosphate + ADP → acetate + ATP
This disproportionation reaction is catalysed by methanogen archaea in their fermentative metabolism. One electron is transferred from the carbonyl function (electron donor) of the carboxylic group to the methyl group (e− acceptor) of acetic acid to respectively produce CO2 and methane gas.
Acetate in biology
Acetate is a common anion in biology. It is mainly utilized by organisms in the form of Acetyl-CoA.Nelson, D. L.; Cox, M. M. "Lehninger, Principles of Biochemistry" 3rd Ed. Worth Publishing: New York, 2000. .
Fermentation of acetyl CoA to acetate
Pyruvate is converted into acetyl-CoA by the enzyme pyruvate dehydrogenase. This acetyl-CoA is then converted into acetate in E. coli, whilst producing ATP by substrate-level phosphorylation. Acetate formation requires two enzymes: phosphate acetyltransferase and acetate kinase.
Fermentation of acetate
Acetic acid can also undergo a dismutation reaction to produce methane and carbon dioxide:
Structures
See also
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