Acetate

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Acetate
Acetate-anion-3D-balls.png
Names
IUPAC name
Acetate
Systematic IUPAC name
Ethanoate
Identifiers
3D model (JSmol)
ChemSpider
PubChem CID
UNII
  • InChI=1S/C2H4O2/c1-2(3)4/h1H3,(H,3,4)/p-1
    Key: QTBSBXVTEAMEQO-UHFFFAOYSA-M
  • InChI=1/C2H4O2/c1-2(3)4/h1H3,(H,3,4)/p-1
    Key: QTBSBXVTEAMEQO-REWHXWOFAL
  • CC(=O)[O-]
Properties
C
2H
3O−
2
Conjugate acid Acetic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

An acetate is a salt formed by the combination of acetic acid with a base (e.g. alkaline, earthy, metallic, nonmetallic or radical base). "Acetate" also describes the conjugate base or ion (specifically, the negatively charged ion called an anion) typically found in aqueous solution and written with the chemical formula C
2H
3O−
2. 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, esters, and the polyatomic anion CH
3CO−
2, or CH
3COO−
.

Contents

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.

Nomenclature and common formula

When part of a salt, the formula of the acetate ion is written as CH
3CO−
2, C
2H
3O−
2, or CH
3COO−
. Chemists often represent acetate as OAc− or, less commonly, AcO−. Thus, HOAc is the symbol for acetic acid, NaOAc for sodium acetate, and EtOAc for ethyl acetate [1] (as Ac is common symbol for acetyl group CH3CO [2] [3] ).The pseudoelement 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 of actinium, the first element of the actinide 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 with peracetic acid when using the OAc abbreviation; for clarity and to avoid errors when translated, HOAc should be avoided in literature mentioning both compounds.

Although its systematic name is ethanoate ( /ɪˈθænoʊ.eɪt/ ), the common acetate remains the preferred IUPAC name. [4]

Salts

acetate anion Acetate-anion-canonical-form-2D-skeletal.png
acetate anion

The acetate anion, [CH3COO]−,(or [C2H3O2]−) is one of the carboxylate family. It is the conjugate base of acetic acid. Above a pH of 5.5, acetic acid converts to acetate: [1]

CH3COOH ⇌ CH3COO− + H+

Many acetate salts are ionic, indicated by their tendency to dissolve well in water. A commonly encountered acetate in the home is sodium acetate, a white solid that can be prepared by combining vinegar and sodium bicarbonate ("bicarbonate of soda"):

CH3COOH + NaHCO3 → CH3COO−Na+ + H2O + CO2

Transition metals 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. [5]

Esters

acetate ester Acetate-ester-2D-skeletal.png
acetate ester

Acetate esters have the general formula CH3CO2R, where R is an organyl 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 of vinyl acetate, precursor to polyvinyl alcohol, which is a component of many paints. 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 acetate discs used in audio record production. Cellulose acetate can be found in many household products. Many industrial solvents are acetates, including methyl acetate, ethyl acetate, isopropyl acetate, ethylhexyl acetate. Butyl acetate is a fragrance used in food products. [5]

Acetate in biology

Acetate is a common anion in biology. It is mainly utilized by organisms in the form of acetyl 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 of ethanol is a major factor in causing hangovers. 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. [7] [8]

Acetate has known immunomodulatory properties and can affect the innate immune response to pathogenic bacteria such as the respiratory pathogen Haemophilus influenzae. [9]

Fermentation acetyl CoA to acetate

Pyruvate is converted into acetyl-coenzyme A (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. [10]

The mixed acid fermentation pathway is characteristic of the family Enterobacteriaceae, which includes E. coli E. coli Bacteria (7316101966).jpg
The mixed acid fermentation pathway is characteristic of the family Enterobacteriaceae, which includes E. coli

    acetyl-CoA + phosphate → acetyl-phosphate + CoA

    acetyl-phosphate + ADP → acetate + ATP

Fermentation of acetate

Acetic acid can also undergo a dismutation reaction to produce methane and carbon dioxide: [11] [12]

CH3COO− + H+ → CH4 + CO2  ΔG° = −36 kJ/mol

This disproportionation reaction is catalysed by methanogen archaea in their fermentative metabolism. One electron is transferred from the carbonyl function (e− donor) of the carboxylic group to the methyl group (e− acceptor) of acetic acid to respectively produce CO2 and methane gas.

Structures

See also

Related Research Articles

<span class="mw-page-title-main">Acid</span> Chemical compound giving a proton or accepting an electron pair

An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen ion, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid.

<span class="mw-page-title-main">Acid–base reaction</span> Chemical reaction between an acid and a base

In chemistry, an acid–base reaction is a chemical reaction that occurs between an acid and a base. It can be used to determine pH via titration. Several theoretical frameworks provide alternative conceptions of the reaction mechanisms and their application in solving related problems; these are called the acid–base theories, for example, Brønsted–Lowry acid–base theory.

<span class="mw-page-title-main">Carboxylic acid</span> Organic compound containing a –C(=O)OH group

In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group attached to an R-group. The general formula of a carboxylic acid is often written as R−COOH or R−CO2H, sometimes as R−C(O)OH with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic acids occur widely. Important examples include the amino acids and fatty acids. Deprotonation of a carboxylic acid gives a carboxylate anion.

<span class="mw-page-title-main">Ester</span> Compound derived from an acid

In chemistry, an ester is a compound derived from an acid in which the hydrogen atom (H) of at least one acidic hydroxyl group of that acid is replaced by an organyl group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well, but not according to the IUPAC.

Hydrolysis is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile.

<span class="mw-page-title-main">Salt (chemistry)</span> Chemical compound involving ionic bonding

In chemistry, a salt or ionic compound is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a neutral compound with no net electric charge. The constituent ions are held together by electrostatic forces termed ionic bonds.

<span class="mw-page-title-main">Acetic anhydride</span> Organic compound with formula (CH₃CO)₂O

Acetic anhydride, or ethanoic anhydride, is the chemical compound with the formula (CH3CO)2O. Commonly abbreviated Ac2O, it is the simplest isolable anhydride of a carboxylic acid and is widely used as a reagent in organic synthesis. It is a colorless liquid that smells strongly of acetic acid, which is formed by its reaction with moisture in the air.

<span class="mw-page-title-main">Sodium acetate</span> Chemical compound

Sodium acetate, CH3COONa, also abbreviated NaOAc, is the sodium salt of acetic acid. This colorless deliquescent salt has a wide range of uses.

<span class="mw-page-title-main">Acetyl chloride</span> Organic compound (CH₃COCl)

Acetyl chloride is an acyl chloride derived from acetic acid. It belongs to the class of organic compounds called acid halides. It is a colorless, corrosive, volatile liquid. Its formula is commonly abbreviated to AcCl.

<span class="mw-page-title-main">Xanthate</span> Salt that is a metal-thioate/O-esters of dithiocarbonate

A xanthate is a salt or ester of a xanthic acid. The formula of the salt of xanthic acid is [R−O−CS2]−M+. Xanthate also refers to the anion [R−O−CS2]−. The formula of a xanthic acid is R−O−C(=S)−S−H, such as ethyl xanthic acid, while the formula of an ester of a xanthic acid is R−O−C(=S)−S−R', where R and R' are organyl groups. The salts of xanthates are also called O-organyl dithioates. The esters of xanthic acid are also called O,S-diorganyl esters of dithiocarbonic acid. The name xanthate is derived from Ancient Greek ξανθός (xanthos) meaning 'yellowish' or 'golden', and indeed most xanthate salts are yellow. They were discovered and named in 1823 by Danish chemist William Christopher Zeise. These organosulfur compounds are important in two areas: the production of cellophane and related polymers from cellulose and for extraction of certain sulphide bearing ores. They are also versatile intermediates in organic synthesis.

<span class="mw-page-title-main">Carboxylate</span> Chemical group (RCOO); conjugate base of a carboxylic acid

In organic chemistry, a carboxylate is the conjugate base of a carboxylic acid, RCOO−. It is an ion with negative charge.

<span class="mw-page-title-main">Calcium acetate</span> Chemical compound

Calcium acetate is a chemical compound which is a calcium salt of acetic acid. It has the formula Ca(C2H3O2)2. Its standard name is calcium acetate, while calcium ethanoate is the systematic name. An older name is acetate of lime. The anhydrous form is very hygroscopic; therefore the monohydrate (Ca(CH3COO)2•H2O) is the common form.

<span class="mw-page-title-main">Mercury(II) acetate</span> Chemical compound

Mercury(II) acetate, also known as mercuric acetate is a chemical compound, the mercury(II) salt of acetic acid, with the formula Hg(O2CCH3)2. Commonly abbreviated Hg(OAc)2, this compound is employed as a reagent to generate organomercury compounds from unsaturated organic precursors. It is a white, water-soluble solid, but some samples can appear yellowish with time owing to decomposition.

In organic chemistry, the acetoxy group, is a functional group with the formula −OCOCH3 and the structure −O−C(=O)−CH3. As the -oxy suffix implies, it differs from the acetyl group by the presence of an additional oxygen atom. The name acetoxy is the short form of acetyl-oxy.

<span class="mw-page-title-main">Acetic acid</span> Colorless and faint organic acid found in vinegar

Acetic acid, systematically named ethanoic acid, is an acidic, colourless liquid and organic compound with the chemical formula CH3COOH. Vinegar is at least 4% acetic acid by volume, making acetic acid the main component of vinegar apart from water. It has been used, as a component of vinegar, throughout history from at least the third century BC.

<span class="mw-page-title-main">Magnesium acetate</span> Chemical compound

Anhydrous magnesium acetate has the chemical formula Mg(C2H3O2)2 and in its hydrated form, magnesium acetate tetrahydrate, it has the chemical formula Mg(CH3COO)2 • 4H2O. In this compound magnesium has an oxidation state of 2+. Magnesium acetate is the magnesium salt of acetic acid. It is deliquescent and upon heating, it decomposes to form magnesium oxide. Magnesium acetate is commonly used as a source of magnesium in biological reactions.

Aluminium triacetate, formally named aluminium acetate, is a chemical compound with composition Al(CH
3CO
2)
3. Under standard conditions it appears as a white, water-soluble solid that decomposes on heating at around 200 °C. The triacetate hydrolyses to a mixture of basic hydroxide / acetate salts, and multiple species co-exist in chemical equilibrium, particularly in aqueous solutions of the acetate ion; the name aluminium acetate is commonly used for this mixed system.

Aluminium sulfacetate is a mixture of aluminium salts dissolved in water with formula Al
2SO
4(CH
3CO
2)
4.

<span class="mw-page-title-main">Europium(III) acetate</span> Chemical compound

Europium(III) acetate is an inorganic salt of europium and acetic acid with the chemical formula of Eu(CH3COO)3. In this compound, europium exhibits the +3 oxidation state. It can exist in the anhydrous form, sesquihydrate and tetrahydrate. Its hydrate molecule is a dimer.

<span class="mw-page-title-main">Holmium acetate</span> Compound of holmium

Holmium acetate is the acetate salt of holmium, with a chemical formula of Ho(CH3COO)3.

References

  1. 1 2 Zumdahl, S. S. “Chemistry” Heath, 1986: Lexington, MA. ISBN   0-669-04529-2.
  2. ↑ International Union of Pure and Applied Chemistry (2005). Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005). Cambridge (UK): RSC – IUPAC . ISBN   0-85404-438-8 . p. 63. Electronic version.
  3. ↑ Brimble, Margaret A.; Black, David StC.; Hartshorn, Richard; Rauter, Amélia P.; Sha, Chin-Kang; Sydnes, Leiv K. (10 November 2012). "Rules for abbreviation of protecting groups (IUPAC Technical Report)". Pure and Applied Chemistry. 85 (1): 310. doi: 10.1351/PAC-REP-12-07-12 . S2CID   55102299.
  4. ↑ R-9.1 Trivial and semisystematic names retained for naming organic compounds Archived 2014-02-08 at the Wayback Machine , A Guide to IUPAC Nomenclature of Organic Compounds, IUPAC Commission on Nomenclature of Organic Chemistry
  5. 1 2 Hosea Cheung, Robin S. Tanke, G. Paul Torrence "Acetic acid" in Ullmann's Encyclopedia of Industrial Chemistry Weinheim, Germany: Wiley-VCH, 2005. doi : 10.1002/14356007.a01_045
  6. ↑ Nelson, D. L.; Cox, M. M. "Lehninger, Principles of Biochemistry" 3rd Ed. Worth Publishing: New York, 2000. ISBN   1-57259-153-6.
  7. ↑ Maxwell, Christina; et al. (2010). "Acetate Causes Alcohol Hangover Headache in Rats". PLOS ONE. 5 (12): e15963. Bibcode:2010PLoSO...515963M. doi: 10.1371/journal.pone.0015963 . PMC   3013144 . PMID   21209842.
  8. ↑ 'Is coffee the real cure for a hangover?' by Bob Holmes, New Scientist, Jan. 15 2011, p. 17.
  9. ↑ Hosmer, Jennifer; Nasreen, Marufa; Dhouib, Rabeb; Essilfie, Ama-Tawiah; Schirra, Horst Joachim; Henningham, Anna; Fantino, Emmanuelle; Sly, Peter; McEwan, Alastair G.; Kappler, Ulrike (2022-01-27). "Access to highly specialized growth substrates and production of epithelial immunomodulatory metabolites determine survival of Haemophilus influenzae in human airway epithelial cells". PLOS Pathogens. 18 (1): e1010209. doi: 10.1371/journal.ppat.1010209 . ISSN   1553-7374. PMC   8794153 . PMID   35085362.
  10. ↑ Keseler, Ingrid M.; et al. (2011). "EcoCyc: a comprehensive database of Escherichia coli biology". Nucleic Acids Research . 39 (Database issue): D583–D590. doi:10.1093/nar/gkq1143. PMC   3013716 . PMID   21097882.
  11. ↑ Ferry, J.G. (1992). "Methane from acetate". Journal of Bacteriology. 174 (17): 5489–5495. doi:10.1128/jb.174.17.5489-5495.1992. PMC   206491 . PMID   1512186.
  12. ↑ Vogels, G. D.; Keltjens, J. T.; Van Der Drift, C. (1988). "Biochemistry of methane production". In Zehnder A.J.B. (ed.). Biology of anaerobic microorganisms. New York: Wiley. pp. 707–770.
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