Anacetate is asalt formed by the combination ofacetic acid with a base (e.g.alkaline,earthy,metallic,nonmetallic or radicalbase). "Acetate" also describes theconjugate base orion (specifically, the negatively charged ion called ananion) typically found inaqueous solution and written with the chemical formulaC 2H 3O− 2. The neutral molecules formed by the combination of the acetate ion and apositive ion (called acation) are also commonly called "acetates" (hence,acetate of lead,acetate of aluminium, etc.). The simplest of these is hydrogen acetate (calledacetic acid) with corresponding salts,esters, and thepolyatomic anionCH 3CO− 2, orCH 3COO− .
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 ofpolymers. In nature, acetate is the most common building block forbiosynthesis.
When part of asalt, the formula of the acetate ion is written asCH 3CO− 2,C 2H 3O− 2, orCH 3COO− . Chemists often represent acetate as OAc− or, less commonly, AcO−. Thus, HOAc is the symbol for acetic acid, NaOAc forsodium acetate, and EtOAc forethyl acetate[1] (as Ac is common symbol foracetyl group CH3CO[2][3]). Thepseudoelement symbol "Ac" is also sometimes encountered in chemical formulas as indicating the entire acetate ion (CH 3CO− 2).[citation needed] It is not to be confused with the symbol ofactinium, the first element of theactinide series; context guides disambiguation. For example, the formula for sodium acetate might be abbreviated as "NaOAc", rather than "NaC2H3O2". Care should also be taken to avoid confusion withperacetic acid when using the OAc abbreviation; for clarity and to avoid errors when translated, HOAc should be avoided in literature mentioning both compounds.
Many acetate salts are ionic, indicated by their tendency to dissolve well in water. A commonly encountered acetate in the home issodium acetate, a white solid that can be prepared by combining vinegar andsodium bicarbonate ("bicarbonate of soda"):
Acetateesters have the general formula CH3CO2R, where R is anorganyl group. The esters are the dominant forms of acetate in the marketplace. Unlike the acetate salts, acetate esters are often liquids, lipophilic, and sometimes volatile. They are popular because they have inoffensive, often sweet odors, they are inexpensive, and they are usually of low toxicity.
Almost half of acetic acid production is consumed in the production ofvinyl acetate, precursor topolyvinyl alcohol, which is a component of manypaints. The second largest use of acetic acid is consumed in the production ofcellulose acetate. In fact, "acetate" is jargon for cellulose acetate, which is used in the production of fibres or diverse products, e.g. theacetate discs used in audio record production. Cellulose acetate can be found in many household products. Many industrialsolvents are acetates, includingmethyl acetate, ethyl acetate,isopropyl acetate, ethylhexyl acetate.Butyl acetate is a fragrance used in food products.[5]
Acetate is a common anion in biology. It is mainly utilized by organisms in the form ofacetyl coenzyme A.[6]
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 ofethanol is a major factor in causinghangovers. Increased serum acetate levels lead to accumulation ofadenosine in many tissues including the brain, and administration of theadenosine receptor antagonistcaffeine to rats after ethanol was found to decreasenociceptive behavior.[7][8]
Acetate has knownimmunomodulatory properties and can affect the innateimmune response topathogenic bacteria such as the respiratory pathogenHaemophilus influenzae.[9]
^abHosea Cheung, Robin S. Tanke, G. Paul Torrence "Acetic acid" inUllmann's Encyclopedia of Industrial Chemistry Weinheim, Germany: Wiley-VCH, 2005.doi:10.1002/14356007.a01_045
^Nelson, D. L.; Cox, M. M. "Lehninger, Principles of Biochemistry" 3rd Ed. Worth Publishing: New York, 2000.ISBN1-57259-153-6.
^Vogels, G. D.; Keltjens, J. T.; Van Der Drift, C. (1988). "Biochemistry of methane production". InZehnder A.J.B. (ed.).Biology of anaerobic microorganisms. New York: Wiley. pp. 707–770.
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