Ethenone

Last updated
Ethenone
Structural formula of ethenone.svg
Ketene-3D-vdW.png
Names
Preferred IUPAC name
Ethenone [1]
Other names
Ketene
Carbomethene
Keto-ethylene
Identifiers
3D model (JSmol)
1098282
ChEBI
ChemSpider
ECHA InfoCard 100.006.671 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 207-336-9
PubChem CID
RTECS number
  • OA7700000
UNII
  • InChI=1S/C2H2O/c1-2-3/h1H2 Yes check.svgY
    Key: CCGKOQOJPYTBIH-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C2H2O/c1-2-3/h1H2
    Key: CCGKOQOJPYTBIH-UHFFFAOYSA-N
  • InChI=1/C2H2O/c1-2-3/h1H2
    Key: CCGKOQOJPYTBIH-UHFFFAOYAO
  • O=C=C
Properties
C2 H2 O
Molar mass 42.037 g/mol
AppearanceColourless gas
Odor penetrating
Density 1.93 g/cm3
Melting point −150.5 °C (−238.9 °F; 122.6 K)
Boiling point −56.1 °C (−69.0 °F; 217.1 K)
decomposes
Solubility soluble in acetone
ethanol
ethyl ether
aromatic solvents
halocarbons
Vapor pressure >1 atm (20°C) [2]
1.4355
Thermochemistry
51.75 J/K mol
-87.24 kJ/mol
Hazards
NFPA 704 (fire diamond)
NFPA 704.svgHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propaneInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
4
4
1
Flash point −107 °C (−161 °F; 166 K)
Explosive limits 5.5-18%
Lethal dose or concentration (LD, LC):
1300 mg/kg (oral, rat)
17 ppm (mouse, 10 min) [3]
23 ppm (mouse, 30 min)
53 ppm (rabbit, 2 hr)
53 ppm (guinea pig, 2 hr)
750 ppm (cat, 10 min)
200 ppm (monkey, 10 min)
50 ppm (mouse, 10 min)
1000 ppm (rabbit, 10 min) [3]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 0.5 ppm (0.9 mg/m3) [2]
REL (Recommended)
TWA 0.5 ppm (0.9 mg/m3) ST 1.5 ppm (3 mg/m3) [2]
IDLH (Immediate danger)
5 ppm [2]
Safety data sheet (SDS) External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

In organic chemistry, ethenone is the formal name for ketene, an organic compound with formula C2H2O or H2C=C=O. It is the simplest member of the ketene class. It is an important reagent for acetylations. [4]

Contents

Properties

Ethenone is a highly reactive gas (at standard conditions) and has a sharp irritating odour. It is only reasonably stable at low temperatures (−80 °C). It must therefore always be prepared for each use and processed immediately, otherwise a dimerization to diketene occurs or it reacts to polymers that are difficult to handle. The polymer content formed during the preparation is reduced, for example, by adding sulfur dioxide to the ketene gas. [5] Because of its cumulative double bonds, ethenone is highly reactive and reacts in an addition reaction H-acidic compounds to the corresponding acetic acid derivatives. It does for example react with water to acetic acid or with primary or secondary amines to the corresponding acetamides.

Preparation

Ethenone is produced by thermal dehydration of acetic acid at 700–750 °C in the presence of triethyl phosphate as a catalyst: [6] [7]

CH3CO2H → CH2=C=O + H2O

It has also been produced on a laboratory scale by the thermolysis of acetone at 600–700 °C. [8] [9]

CH3COCH3 →CH2=C=O + CH4

This reaction is called the Schmidlin ketene synthesis. [10]

On a laboratory scale it can be produced by the thermal decomposition of Meldrum's acid at temperatures greater than 200 °C.[ citation needed ]

History

When passed through heated pipes or electrically heated metal (like copper) wires at 500-600 °C in the presence of carbon disulfide, acetone decomposes into methane and ethenone, with 95% yield. [11] [12] Ethenone was discovered at the same time by Hermann Staudinger (by reaction of bromoacetyl bromide with metallic zinc) [13] [14] The dehydration of acetic acid was reported in 1910. [15]

Ethenone synthesis from bromoacetyl bromide.png

The thermal decomposition of acetic anhydride was also described. [16]

Ethenone synthesis from acetic anhydride.png
Ethenone synthesis from acetone.png
Ethenone synthesis from acetic acid.png

Natural occurrence

Ethenone has been observed to occur in space, in comets or in gas as part of the interstellar medium. [17]

Use

Ethenone is used to make acetic anhydride from acetic acid. Generally it is used for the acetylation of chemical compounds. [18]

Reactions with ammonia, water, ethanol, and acetic acid Ketene reactions.png
Reactions with ammonia, water, ethanol, and acetic acid
Mechanism of the above reactions Mechanism-Ketene Reactions V1.svg
Mechanism of the above reactions

Ethenone reacts with methanal in the presence of catalysts such as Lewis acids (AlCl3, ZnCl2 or BF3) to give β-propiolactone. [19] The technically most significant use of ethenone is the synthesis of sorbic acid by reaction with 2-butenal (crotonaldehyde) in toluene at about 50 °C in the presence of zinc salts of long-chain carboxylic acids. This produces a polyester of 3-hydroxy-4-hexenoic acid, which is thermally [20] or hydrolytically depolymerized to sorbic acid.

Ethenone is very reactive, tending to react with nucleophiles to form an acetyl group. For example, it reacts with water to form acetic acid; [21] with acetic acid to form acetic anhydride; with ammonia and amines to form ethanamides; [22] and with dry hydrogen halides to form acetyl halides. [23]

The formation of acetic acid likely occurs by an initial formation of 1,1-dihydroxyethene, which then tautomerizes to give the final product. [24]

Ethenone will also react with itself via [2 + 2] photocycloadditions to form cyclic dimers known as diketenes. For this reason, it should not be stored for long periods. [25]

Hazards

Exposure to concentrated levels causes humans to experience irritation of body parts such as the eye, nose, throat and lungs. Extended toxicity testing on mice, rats, guinea pigs and rabbits showed that ten-minute exposures to concentrations of freshly generated ethenone as low as 0.2 mg/liter (116 ppm) may produce a high percentage of deaths in small animals. These findings show ethenone is toxicologically identical to phosgene. [26] [18]

The formation of ketene in the pyrolysis of vitamin E acetate, an additive of some e-liquid products, is one possible mechanism of the reported pulmonary damage [27] caused by electronic cigarette use. [28] A number of patents describe the catalytic formation of ketene from carboxylic acids and acetates, using a variety of metals or ceramics, some of which are known to occur in e-cigarette devices from patients with e-cigarette or vaping product-use associated lung injury (EVALI). [29] [30]

Occupational exposure limits are set at 0.5 ppm (0.9 mg/m3) over an eight-hour time-weighted average. [31] An IDLH limit is set at 5 ppm, as this is the lowest concentration productive of a clinically relevant physiologic response in humans. [32]

Related Research Articles

<span class="mw-page-title-main">Ketene</span> Organic compound of the form >C=C=O

In organic chemistry, a ketene is an organic compound of the form RR'C=C=O, where R and R' are two arbitrary monovalent chemical groups. The name may also refer to the specific compound ethenone H2C=C=O, the simplest ketene.

Pyrrole is a heterocyclic, aromatic, organic compound, a five-membered ring with the formula C4H4NH. It is a colorless volatile liquid that darkens readily upon exposure to air. Substituted derivatives are also called pyrroles, e.g., N-methylpyrrole, C4H4NCH3. Porphobilinogen, a trisubstituted pyrrole, is the biosynthetic precursor to many natural products such as heme.

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

N,N-Dimethylaniline (DMA) is an organic chemical compound, a substituted derivative of aniline. It is a tertiary amine, featuring a dimethylamino group attached to a phenyl group. This oily liquid is colourless when pure, but commercial samples are often yellow. It is an important precursor to dyes such as crystal violet.

<span class="mw-page-title-main">Phthalic anhydride</span> Chemical compound

Phthalic anhydride is the organic compound with the formula C6H4(CO)2O. It is the anhydride of phthalic acid. Phthalic anhydride is a principal commercial form of phthalic acid. It was the first anhydride of a dicarboxylic acid to be used commercially. This white solid is an important industrial chemical, especially for the large-scale production of plasticizers for plastics. In 2000, the worldwide production volume was estimated to be about 3 million tonnes per year.

In organic chemistry, an acyl chloride is an organic compound with the functional group −C(=O)Cl. Their formula is usually written R−COCl, where R is a side chain. They are reactive derivatives of carboxylic acids. A specific example of an acyl chloride is acetyl chloride, CH3COCl. Acyl chlorides are the most important subset of acyl halides.

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

In organic chemistry, an acyl halide is a chemical compound derived from an oxoacid by replacing a hydroxyl group with a halide group.

<span class="mw-page-title-main">Diazomethane</span> Simplest diazo compound and methylating agent

Diazomethane is an organic chemical compound with the formula CH2N2, discovered by German chemist Hans von Pechmann in 1894. It is the simplest diazo compound. In the pure form at room temperature, it is an extremely sensitive explosive yellow gas; thus, it is almost universally used as a solution in diethyl ether. The compound is a popular methylating agent in the laboratory, but it is too hazardous to be employed on an industrial scale without special precautions. Use of diazomethane has been significantly reduced by the introduction of the safer and equivalent reagent trimethylsilyldiazomethane.

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.

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

Resorcinol (or resorcin) is a phenolic compound. It is an organic compound with the formula C6H4(OH)2. It is one of three isomeric benzenediols, the 1,3-isomer (or meta-isomer). Resorcinol crystallizes from benzene as colorless needles that are readily soluble in water, alcohol, and ether, but insoluble in chloroform and carbon disulfide.

<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.

The Pummerer rearrangement is an organic reaction whereby an alkyl sulfoxide rearranges to an α-acyloxy–thioether (monothioacetal-ester) in the presence of acetic anhydride.

<span class="mw-page-title-main">Indene</span> Bicyclic hydrocarbon compound with formula C9H8

Indene is an aromatic, polycyclic hydrocarbon with chemical formula C9H8. It is composed of a benzene ring fused with a cyclopentene ring. This flammable liquid is colorless although samples often are pale yellow. The principal industrial use of indene is in the production of indene/coumarone thermoplastic resins. Substituted indenes and their closely related indane derivatives are important structural motifs found in many natural products and biologically active molecules, such as sulindac.

<span class="mw-page-title-main">Knorr pyrrole synthesis</span> Chemical reaction

The Knorr pyrrole synthesis is a widely used chemical reaction that synthesizes substituted pyrroles (3). The method involves the reaction of an α-amino-ketone (1) and a compound containing an electron-withdrawing group α to a carbonyl group (2).

The Dakin–West reaction is a chemical reaction that transforms an amino-acid into a keto-amide using an acid anhydride and a base, typically pyridine. It is named for Henry Drysdale Dakin (1880–1952) and Randolph West (1890–1949). In 2016 Schreiner and coworkers reported the first asymmetric variant of this reaction employing short oligopeptides as catalysts.

<span class="mw-page-title-main">Crotonic acid</span> Chemical compound

Crotonic acid ((2E)-but-2-enoic acid) is a short-chain unsaturated carboxylic acid described by the formula CH3CH=CHCO2H. The name crotonic acid was given because it was erroneously thought to be a saponification product of croton oil. It crystallizes as colorless needles from hot water. With a cis-alkene, Isocrotonic acid is an isomer of crotonic acid. Crotonic acid is soluble in water and many organic solvents. Its odor is similar to that of butyric acid.

<span class="mw-page-title-main">1,4-Benzoquinone</span> Chemical compound

1,4-Benzoquinone, commonly known as para-quinone, is a chemical compound with the formula C6H4O2. In a pure state, it forms bright-yellow crystals with a characteristic irritating odor, resembling that of chlorine, bleach, and hot plastic or formaldehyde. This six-membered ring compound is the oxidized derivative of 1,4-hydroquinone. The molecule is multifunctional: it exhibits properties of a ketone, being able to form oximes; an oxidant, forming the dihydroxy derivative; and an alkene, undergoing addition reactions, especially those typical for α,β-unsaturated ketones. 1,4-Benzoquinone is sensitive toward both strong mineral acids and alkali, which cause condensation and decomposition of the compound.

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

Diphenylketene is a chemical substance of the ketene family. Diphenylketene, like most stable disubstituted ketenes, is a red-orange oil at room temperature and pressure. Due to the successive double bonds in the ketene structure R1R2C=C=O, diphenyl ketene is a heterocumulene. The most important reaction of diphenyl ketene is the [2+2] cycloaddition at C-C, C-N, C-O, and C-S multiple bonds.

<span class="mw-page-title-main">Diketene</span> Organic compound with formula (CH2CO)2

Diketene is an organic compound with the molecular formula C4H4O2, and which is sometimes written as (CH2CO)2. It is formed by dimerization of ketene, H2C=C=O. Diketene is a member of the oxetane family. It is used as a reagent in organic chemistry. It is a colorless liquid.

<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">Alkyl ketene dimer</span> Class of chemical compounds

Alkyl ketene dimers (AKDs) are a family of organic compounds based on the 4-membered ring system of oxetan-2-one, which is also the central structural element of propiolactone and diketene. Attached to the oxetane ring of technically relevant alkyl ketene dimers there is a C12 – C16 alkyl group in the 3-position and a C13 – C17 alkylidene group in the 4-position.

References

  1. ↑ "Front Matter". Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 723. doi:10.1039/9781849733069-FP001. ISBN   978-0-85404-182-4.
  2. 1 2 3 4 NIOSH Pocket Guide to Chemical Hazards. "#0367". National Institute for Occupational Safety and Health (NIOSH).
  3. 1 2 "Ketene". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  4. ↑ Miller, Raimund; Abaecherli, Claudio; Said, Adel; Jackson, Barry (2001). "Ketenes". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a15_063. ISBN   978-3527306732.
  5. ↑ EP 0377438,R. Bergamin et al.,issued 1990-06-11, assigned to Lonza AG
  6. ↑ Miller, Raimund; Abaecherli, Claudio; Said, Adel; Jackson, Barry (2001). "Ketenes". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a15_063. ISBN   978-3-527-30385-4.
  7. ↑ Arpe, Hans-Jürgen (2007), Industrielle organische Chemie: Bedeutende vor- und Zwischenprodukte (in German) (6th ed.), Weinheim: Wiley-VCH, pp. 200–1, ISBN   978-3-527-31540-6 [ permanent dead link ]
  8. ↑ Weygand C (1972). Hilgetag G, Martini A (eds.). Weygand/Hilgetag Preparative Organic Chemistry (4th ed.). New York: John Wiley & Sons, Inc. pp. 1031–1032. ISBN   978-0471937494.
  9. ↑ Hurd CD, Kamm O (1941). "Ketene in Organic Syntheses". Organic Syntheses. Vol. Collective Vol. 1. p. 330.
  10. ↑ Schmidlin J, Bergman M (1910). "Darstellung des Ketens aus Aceton" [Preparation of ketene from acetone]. Berichte der Deutschen Chemischen Gesellschaft (in German). 43 (3): 2821–2823. doi:10.1002/cber.19100430340.
  11. ↑ K.-H. Lautenschläger, W. Schröter, A. Wanninger, "Taschenbuch der Chemie", 20. Aufl. 2006, ISBN   978-3-8171-1761-1.
  12. ↑ "Ketene". Organic Syntheses . doi:10.15227/orgsyn.004.0039 .
  13. ↑ H. Staudinger H. W. Klever (1908): "Keten. Bemerkung zur Abhandlung zur Abhandlung der HHrn. V.T. Wilsmore und A. W. Stewart". Berichte der deutschen chemischen Gesellschaft, volume 41, issue 1, pages 1516-1517. doi : 10.1002/cber.190804101275
  14. ↑ Tidwell, T. T. (2005), "Ein Jahrhundert Ketene (1905–2005): die Entdeckung einer vielseitigen Klasse reaktiver Intermediate". Angewandte Chemie, volume 117, pages 5926–5933. doi : 10.1002/ange.200500098
  15. ↑ J. Schmidlin, M. Bergman (1910): Berichte der deutschen chemischen Gesellschaft, volume 43, pages 2821-. doi : 10.1002/cber.19100430340.
  16. ↑ Norman Thomas Mortimer Wilsmore (1907): "Keten". Journal of the Chemical Society, Transactions, volume 91, article CLXXXVIII (188), pages 1938-1941. doi : 10.1039/ct9079101938
  17. ↑ Hudson, Reggie L.; Loeffler, Mark J. (31 July 2013). "Ketene Formation in Interstellar Ices: A Laboratory Study". The Astrophysical Journal. 773 (2): 109. Bibcode:2013ApJ...773..109H. doi:10.1088/0004-637x/773/2/109. hdl: 2060/20140010162 . S2CID   37437108.
  18. 1 2 Entry on Diketen . at: Römpp Online . Georg Thieme Verlag, retrieved 16. Juni 2014.
  19. ↑ Hans-Jürgen Arpe, "Industrielle Organische Chemie", 6. Aufl., 2007, WILEY-VCH Verlag, Weinheim, ISBN   978-3-527-31540-6.
  20. ↑ EP 1295860,D. Decker et al.,issued 26. März 2003-03-26, assigned to Nutrinova GmbH
  21. ↑ Tidwell, p. 11.
  22. ↑ Tidwell, p. 560.
  23. ↑ ChemSpider http://www.chemspider.com/Chemical-Structure.9643.html
  24. ↑ Nguyen, Minh Tho; Raspoet, Greet (1999). "The hydration mechanism of ketene: 15 years later". Can. J. Chem. 77 (5–6): 817–829. doi:10.1139/v99-090.
  25. ↑ Christoph Taeschler :Ketenes, Ketene Dimers, and Related Substances, Kirk-Othmer Encyclopedia of Chemical Technology, John Wiley & Sons, New York, 2010
  26. ↑ H. A. Wooster; C. C. Lushbaugh; C. E. Redeman (1946). "The Inhalation Toxicity of Ketene and of Ketene Dimer". J. Am. Chem. Soc. 68 (12): 2743. doi:10.1021/ja01216a526.
  27. ↑ "The Vaping-Related Lung Disease Outbreak May be Coming to an End". 20 December 2019.
  28. ↑ Wu, Dan; O’Shea, Donal F. (24 March 2020). "Potential for release of pulmonary toxic ketene from vaping pyrolysis of vitamin E acetate". Proceedings of the National Academy of Sciences. 117 (12): 6349–6355. Bibcode:2020PNAS..117.6349W. doi: 10.1073/pnas.1920925117 . PMC   7104367 . PMID   32156732.
  29. ↑ Attfield, Kathleen R.; Chen, Wenhao; Cummings, Kristin J.; Jacob, Peyton; O’Shea, Donal F.; Wagner, Jeff; Wang, Ping; Fowles, Jefferson (15 October 2020). "Potential of Ethenone (Ketene) to Contribute to Electronic Cigarette, or Vaping, Product Use–associated Lung Injury". American Journal of Respiratory and Critical Care Medicine. 202 (8): 1187–1189. doi:10.1164/rccm.202003-0654LE. PMID   32551843. S2CID   219919028.
  30. ↑ U.S. patent No. 5475144. Catalyst and process for synthesis of ketenes from carboxylic acids. Dec 12, 1995. https://patents.google.com/patent/US5475144A/en
  31. ↑ Centers for Disease Control and Prevention (4 April 2013). "Ketene". NIOSH Pocket Guide to Chemical Hazards. Retrieved 13 November 2013.
  32. ↑ Centers for Disease Control and Prevention (May 1994). "Ketene". Documentation for Immediately Dangerous To Life or Health Concentrations (IDLHs). Retrieved 13 November 2013.

Literature

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