Acetyl group

Acetyl group
	Skeletal formula of acetyl with all implicit hydrogens shown
Names
	IUPAC name Acetyl (preferred to ethanoyl)
	Systematic IUPAC name Methyloxidocarbon(•) (additive)
Identifiers
CAS Number	3170-69-2 ;
3D model (JSmol)	Interactive image ;
Abbreviations	Ac
Beilstein Reference	1697938
ChEBI	CHEBI:46887 ;
ChemSpider	121499 ;
Gmelin Reference	786
PubChem CID	137849 ;
	InChI InChI=1S/C2H3O/c1-2-3/h1H3 Key: TUCNEACPLKLKNU-UHFFFAOYSA-N ;
	SMILES C[C]=O;
Properties
Chemical formula	C2H3O
Molar mass	43.045 g·mol−1
Thermochemistry
Std enthalpy of; formation (ΔfH⦵298)	−15 to −9 kJ mol−1
Related compounds
Related compounds	Acetone ; Carbon monoxide ; Acetic acid
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Last updated January 27, 2025

In organic chemistry, an acetyl group is a functional group denoted by the chemical formula −COCH₃ and the structure −C(=O)−CH₃. It is sometimes represented by the symbol Ac^[5]^[6] (not to be confused with the element actinium). In IUPAC nomenclature, an acetyl group is called an ethanoylgroup.

Acetylation

The process of adding an acetyl group into a molecule is called acetylation. An example of an acetylation reaction is the conversion of glycine to N-acetylglycine:^[7]

H₂NCH₂CO₂H + (CH₃CO)₂O → CH₃C(O)NHCH₂CO₂H + CH₃CO₂H

In biology

Enzymes which perform acetylation on proteins or other biomolecules are known as acetyltransferases. In biological organisms, acetyl groups are commonly transferred from acetyl-CoA to other organic molecules. Acetyl-CoA is an intermediate in the biological synthesis and in the breakdown of many organic molecules. Acetyl-CoA is also created during the second stage of cellular respiration (pyruvate decarboxylation) by the action of pyruvate dehydrogenase on pyruvic acid.^[8]

Proteins are often modified via acetylation, for various purposes. For example, acetylation of histones by histone acetyltransferases (HATs) results in an expansion of local chromatin structure, allowing transcription to occur by enabling RNA polymerase to access DNA. However, removal of the acetyl group by histone deacetylases (HDACs) condenses the local chromatin structure, thereby preventing transcription.^[9]

In synthetic organic and pharmaceutical chemistry

Acetylation can be achieved by chemists using a variety of methods, most commonly with the use of acetic anhydride or acetyl chloride, often in the presence of a tertiary or aromatic amine base.

Pharmacology

Acetylated organic molecules exhibit increased ability to cross the selectively permeable blood–brain barrier.^[10] Acetylation helps a given drug reach the brain more quickly, making the drug's effects more intense and increasing the effectiveness of a given dose.^{[ citation needed ]} The acetyl group in acetylsalicylic acid (aspirin) enhances its effectiveness relative to the natural anti-inflammatant salicylic acid. In similar manner, acetylation converts the natural painkiller morphine into the far more potent heroin (diacetylmorphine).^[10]

There is some evidence that acetyl-L-carnitine may be more effective for some applications than L-carnitine.^[11] Acetylation of resveratrol holds promise as one of the first anti-radiation medicines for human populations.^[12]

Etymology

The term "acetyl" was coined by the German chemist Justus von Liebig in 1839 CE to describe what he incorrectly believed to be the radical of acetic acid (the main component of vinegar, aside from water), which is now known as the vinyl group (coined in 1851 CE); "acetyl" is derived from the Latin acētum, meaning "vinegar." When it was shown that Liebig's theory was wrong and acetic acid had a different radical, his name was carried over to the correct one, but the name of acetylene (coined in 1860 CE) was retained.^[13]

Related Research Articles

In organic chemistry, a vinyl group is a functional group with the formula −CH=CH₂. It is the ethylene molecule with one fewer hydrogen atom. The name is also used for any compound containing that group, namely R−CH=CH₂ where R is any other group of atoms.

Alanine, or α-alanine, is an α-amino acid that is used in the biosynthesis of proteins. It contains an amine group and a carboxylic acid group, both attached to the central carbon atom which also carries a methyl group side chain. Consequently it is classified as a nonpolar, aliphatic α-amino acid. Under biological conditions, it exists in its zwitterionic form with its amine group protonated and its carboxyl group deprotonated. It is non-essential to humans as it can be synthesized metabolically and does not need to be present in the diet. It is encoded by all codons starting with GC.

Pyruvic acid (CH₃COCOOH) is the simplest of the alpha-keto acids, with a carboxylic acid and a ketone functional group. Pyruvate, the conjugate base, CH₃COCOO⁻, is an intermediate in several metabolic pathways throughout the cell.

Acetyl-CoA is a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. Its main function is to deliver the acetyl group to the citric acid cycle to be oxidized for energy production.

<span class="mw-page-title-main">Acetate</span> Salt compound formed from acetic acid and a base

An acetate is a salt formed by the combination of acetic acid with a base. "Acetate" also describes the conjugate base or ion 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 are also commonly called "acetates". The simplest of these is hydrogen acetate with corresponding salts, esters, and the polyatomic anion CH^₃CO⁻
₂, or CH^₃COO⁻
.

In chemical nomenclature, the IUPAC nomenclature of organic chemistry is a method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry (IUPAC). It is published in the Nomenclature of Organic Chemistry. Ideally, every possible organic compound should have a name from which an unambiguous structural formula can be created. There is also an IUPAC nomenclature of inorganic chemistry.

In biochemistry, a transferase is any one of a class of enzymes that catalyse the transfer of specific functional groups from one molecule to another. They are involved in hundreds of different biochemical pathways throughout biology, and are integral to some of life's most important processes.

<span class="mw-page-title-main">Histone acetyltransferase</span> Enzymes that catalyze acyl group transfer from acetyl-CoA to histones

Histone acetyltransferases (HATs) are enzymes that acetylate conserved lysine amino acids on histone proteins by transferring an acetyl group from acetyl-CoA to form ε-N-acetyllysine. DNA is wrapped around histones, and, by transferring an acetyl group to the histones, genes can be turned on and off. In general, histone acetylation increases gene expression.

<span class="mw-page-title-main">Acyl halide</span> Oxoacid compound with an –OH group replaced by a halogen

An acyl halide is a chemical compound derived from an oxoacid by replacing a hydroxyl group with a halide group.

In chemistry, acetylation is an organic esterification reaction with acetic acid. It introduces an acetyl group into a chemical compound. Such compounds are termed acetate esters or simply acetates. Deacetylation is the opposite reaction, the removal of an acetyl group from a chemical compound.

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">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.

An organic acid anhydride is an acid anhydride that is also an organic compound. An acid anhydride is a compound that has two acyl groups bonded to the same oxygen atom. A common type of organic acid anhydride is a carboxylic anhydride, where the parent acid is a carboxylic acid, the formula of the anhydride being (RC(O))₂O. Symmetrical acid anhydrides of this type are named by replacing the word acid in the name of the parent carboxylic acid by the word anhydride. Thus, (CH₃CO)₂O is called acetic anhydride.Mixed (or unsymmetrical) acid anhydrides, such as acetic formic anhydride (see below), are known, whereby reaction occurs between two different carboxylic acids. Nomenclature of unsymmetrical acid anhydrides list the names of both of the reacted carboxylic acids before the word "anhydride" (for example, the dehydration reaction between benzoic acid and propanoic acid would yield "benzoic propanoic anhydride").

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.

Histone acetylation and deacetylation are the processes by which the lysine residues within the N-terminal tail protruding from the histone core of the nucleosome are acetylated and deacetylated as part of gene regulation.

Carnitine palmitoyltransferase I (CPT1) also known as carnitine acyltransferase I, CPTI, CAT1, CoA:carnitine acyl transferase (CCAT), or palmitoylCoA transferase I, is a mitochondrial enzyme responsible for the formation of acyl carnitines by catalyzing the transfer of the acyl group of a long-chain fatty acyl-CoA from coenzyme A to l-carnitine. The product is often palmitoylcarnitine, but other fatty acids may also be substrates. It is part of a family of enzymes called carnitine acyltransferases. This "preparation" allows for subsequent movement of the acyl carnitine from the cytosol into the intermembrane space of mitochondria.

Acetyl-CoA synthetase (ACS) or Acetate—CoA ligase is an enzyme involved in metabolism of acetate. It is in the ligase class of enzymes, meaning that it catalyzes the formation of a new chemical bond between two large molecules.

Carnitine O-acetyltransferase also called carnitine acetyltransferase is an enzyme that encoded by the CRAT gene that catalyzes the chemical reaction

In chemical nomenclature, a preferred IUPAC name (PIN) is a unique name, assigned to a chemical substance and preferred among all possible names generated by IUPAC nomenclature. The "preferred IUPAC nomenclature" provides a set of rules for choosing between multiple possibilities in situations where it is important to decide on a unique name. It is intended for use in legal and regulatory situations.

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.

References

↑ "List of Radical Names Beginning from "A"". Nomenclature of Organic Chemistry, Sections A, B, C, D, E, F, and H, Pergamon Press, Oxford, 1979. Copyright 1979 IUPAC.
↑ "R-5.7.1 Carboxylic acids, where acetyl appears as an example". IUPAC, Commission on Nomenclature of Organic Chemistry. A Guide to IUPAC Nomenclature of Organic Compounds (Recommendations 1993), 1993, Blackwell Scientific publications, Copyright 1993 IUPAC.
↑ IUPAC Chemical Nomenclature and Structure Representation Division (2013). "P-65.1.7.2.1". In Favre, Henri A.; Powell, Warren H. (eds.). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. IUPAC–RSC. ISBN 978-0-85404-182-4.
↑ "Acetyl". Chemical Entities of Biological Interest. UK: European Bioinformatics Institute.
↑ Banik, Gregory M.; Baysinger, Grace; Kamat, Prashant V.; Pienta, Norbert, eds. (January 2020). The ACS Guide to Scholarly Communication. Washington, DC: American Chemical Society. doi:10.1021/acsguide.50308. ISBN 978-0-8412-3586-1. S2CID 262269861.
↑ Hanson, James A. (2001). Functional group chemistry. Cambridge, Eng: Royal Society of Chemistry. p. 11. ISBN 0-85404-627-5.
↑ Herbst, R. M.; Shemin, D. (1943). "Acetylglycine". Organic Syntheses ; Collected Volumes, vol. 2, p. 11.
↑ Patel, Mulchand (June 13, 2014). "The Pyruvate Dehydrogenase Complexes: Structure-based Function and Regulation". The Journal of Biological Chemistry. 289 (24): 16615–16623. doi: 10.1074/jbc.R114.563148 . PMC 4059105 . PMID 24798336.
↑ Nelson, David L.; Cox, Michael M. (2000). Lehninger principles of biochemistry (3rd ed.). New York: Worth Publishers. ISBN 1-57259-153-6.
1 2 Pardridge, William M (2012-08-29). "Drug Transport across the Blood–Brain Barrier". Journal of Cerebral Blood Flow & Metabolism. 32 (11): 1959–1972. doi:10.1038/jcbfm.2012.126. ISSN 0271-678X. Archived from the original on 2025-01-01.
↑ Liu, J; Head, E; Kuratsune, H; Cotman, C. W.; Ames, B. N. (2004). "Comparison of the effects of L-carnitine and acetyl-L-carnitine on carnitine levels, ambulatory activity, and oxidative stress biomarkers in the brain of old rats". Annals of the New York Academy of Sciences. 1033 (1): 117–31. Bibcode:2004NYASA1033..117L. doi:10.1196/annals.1320.011. PMID 15591009. S2CID 24221474.
↑ Koide, Kazunori; Osman, Sami; Garner, Amanda L.; Song, Fengling; Dixon, Tracy; Greenberger, Joel S.; Epperly, Michael W. (14 April 2011). "The Use of 3,5,4′-Tri-acetylresveratrol as a Potential Prodrug for Resveratrol Protects Mice from γ-Irradiation-Induced Death". ACS Medicinal Chemistry Letters. 2 (4): 270–274. doi:10.1021/ml100159p. PMC 3151144 . PMID 21826253.
↑ Constable, Edwin C.; Housecroft, Catherine E. (2020-04-20). "Before Radicals Were Free – the Radical Particulier of de Morveau". Chemistry. 2 (2): 293–304. doi: 10.3390/chemistry2020019 . ISSN 2624-8549.

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[1] "List of Radical Names Beginning from "A"". Nomenclature of Organic Chemistry, Sections A, B, C, D, E, F, and H, Pergamon Press, Oxford, 1979. Copyright 1979 IUPAC.

[2] "R-5.7.1 Carboxylic acids, where acetyl appears as an example". IUPAC, Commission on Nomenclature of Organic Chemistry. A Guide to IUPAC Nomenclature of Organic Compounds (Recommendations 1993), 1993, Blackwell Scientific publications, Copyright 1993 IUPAC.

[3] IUPAC Chemical Nomenclature and Structure Representation Division (2013). "P-65.1.7.2.1". In Favre, Henri A.; Powell, Warren H. (eds.). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. IUPAC–RSC. ISBN 978-0-85404-182-4.

[4] "Acetyl". Chemical Entities of Biological Interest. UK: European Bioinformatics Institute.

[5] Banik, Gregory M.; Baysinger, Grace; Kamat, Prashant V.; Pienta, Norbert, eds. (January 2020). The ACS Guide to Scholarly Communication. Washington, DC: American Chemical Society. doi:10.1021/acsguide.50308. ISBN 978-0-8412-3586-1. S2CID 262269861.

[isbn0-85404-627-5-6] Hanson, James A. (2001). Functional group chemistry. Cambridge, Eng: Royal Society of Chemistry. p. 11. ISBN 0-85404-627-5.

[7] Herbst, R. M.; Shemin, D. (1943). "Acetylglycine". Organic Syntheses ; Collected Volumes, vol. 2, p. 11.

[8] Patel, Mulchand (June 13, 2014). "The Pyruvate Dehydrogenase Complexes: Structure-based Function and Regulation". The Journal of Biological Chemistry. 289 (24): 16615–16623. doi: 10.1074/jbc.R114.563148 . PMC 4059105 . PMID 24798336.

[9] Nelson, David L.; Cox, Michael M. (2000). Lehninger principles of biochemistry (3rd ed.). New York: Worth Publishers. ISBN 1-57259-153-6.

[:0-10] 1 2 Pardridge, William M (2012-08-29). "Drug Transport across the Blood–Brain Barrier". Journal of Cerebral Blood Flow & Metabolism. 32 (11): 1959–1972. doi:10.1038/jcbfm.2012.126. ISSN 0271-678X. Archived from the original on 2025-01-01.

[11] Liu, J; Head, E; Kuratsune, H; Cotman, C. W.; Ames, B. N. (2004). "Comparison of the effects of L-carnitine and acetyl-L-carnitine on carnitine levels, ambulatory activity, and oxidative stress biomarkers in the brain of old rats". Annals of the New York Academy of Sciences. 1033 (1): 117–31. Bibcode:2004NYASA1033..117L. doi:10.1196/annals.1320.011. PMID 15591009. S2CID 24221474.

[12] Koide, Kazunori; Osman, Sami; Garner, Amanda L.; Song, Fengling; Dixon, Tracy; Greenberger, Joel S.; Epperly, Michael W. (14 April 2011). "The Use of 3,5,4′-Tri-acetylresveratrol as a Potential Prodrug for Resveratrol Protects Mice from γ-Irradiation-Induced Death". ACS Medicinal Chemistry Letters. 2 (4): 270–274. doi:10.1021/ml100159p. PMC 3151144 . PMID 21826253.

[13] Constable, Edwin C.; Housecroft, Catherine E. (2020-04-20). "Before Radicals Were Free – the Radical Particulier of de Morveau". Chemistry. 2 (2): 293–304. doi: 10.3390/chemistry2020019 . ISSN 2624-8549.

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