Diketene

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Diketene
Diketene-2D-skeletal.png
Diketene-from-xtal-3D-balls.png
Names
Preferred IUPAC name
4-Methylideneoxetan-2-one
Other names
γ-Methylenepropiolactone
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.010.562 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 211-617-1
PubChem CID
RTECS number
  • RQ8225000
UNII
UN number 2521
  • InChI=1S/C4H4O2/c1-3-2-4(5)6-3/h1-2H2 Yes check.svgY
    Key: WASQWSOJHCZDFK-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C4H4O2/c1-3-2-4(5)6-3/h1-2H2
    Key: WASQWSOJHCZDFK-UHFFFAOYAM
  • O=C1OC(=C)C1
Properties
C4H4O2
Molar mass 84.074 g·mol−1
Density 1.09 g cm−3
Melting point −7 °C (19 °F; 266 K)
Boiling point 127 °C (261 °F; 400 K)
Viscosity 0.88 mPa.s
Hazards
GHS labelling:
GHS-pictogram-flamme.svg GHS-pictogram-acid.svg GHS-pictogram-skull.svg GHS-pictogram-exclam.svg
Danger
H226, H301, H302, H315, H318, H330, H331, H332, H335
P210, P233, P240, P241, P242, P243, P260, P261, P264, P270, P271, P280, P284, P301+P310, P301+P312, P302+P352, P303+P361+P353, P304+P312, P304+P340, P305+P351+P338, P310, P311, P312, P320, P321, P330, P332+P313, P362, P370+P378, P403+P233, P403+P235, P405, P501
Flash point 33 °C (91 °F; 306 K)
275
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

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. [1] It is a colorless liquid.

Contents

Production

Diketene is produced on commercial scale by dimerization of ketene. [2]

Reactions

Heating or irradiation with UV light [3] regenerates the ketene monomer:

(C2H2O)2 ⇌ 2 CH2CO

Alkylated ketenes also dimerize with ease and form substituted diketenes.

Diketene readily hydrolyzes in water forming acetoacetic acid. Its half-life in water is approximately 45 min. a 25 °C at 2 < pH < 7. [4]

Certain diketenes with two aliphatic chains, such as alkyl ketene dimers (AKDs), are used industrially to improve hydrophobicity in paper.

At one time acetic anhydride was prepared by the reaction of ketene with acetic acid: [5]

H2C=C=O + CH3COOH → (CH3CO)2O   ΔH = −63 kJ/mol

Acetoacetylation

Diketene also reacts with alcohols and amines to the corresponding acetoacetic acid derivatives. The process is sometimes called acetoacetylation. An example is the reaction with 2-aminoindane: [6]

DiketeneReaction.svg

Diketene is an important industrial intermediate used for the production of acetoacetate esters and amides as well as substituted 1-phenyl-3-methylpyrazolones. The latter are used in the manufacture of dyestuffs and pigments. [7] A typical reaction is:

ArNH2 + (CH2CO)2 → ArNHC(O)CH2C(O)CH3

These acetoacetamides are precursors to arylide yellow and diarylide pigments. [8]

Use

Diketenes with two alkyl chains are used in the manufacture of paper for sizing of paper in order to improve their printability (by hydrophobization). Besides the rosin resins with about 60% share of world consumption, long chain diketenes called alkylketene dimers (AKD) are with 16% share the most important synthetic paper sizes, they are usually used in concentrations of 0.15%, meaning 1.5 kg solid AKD/t paper.

The preparation of AKD is carried out by chlorination of long chain fatty acids (such as stearic acid, using chlorinating agents such as thionyl chloride) to give the corresponding acid chlorides and subsequent elimination of HCl by amines (for example triethylamine) in toluene or other solvents: [9]

AKD synthesis 2.svg

Furthermore, diketenes are used as intermediates in the manufacture of pharmaceuticals, insecticides and dyes. For example pyrazolones are formed from substituted phenylhydrazines, they were used as analgetics but are now largely obsolete. With methylamine diketene reacts to give N,N'-dimethylacetoacetamide, a precursor to the (controversial) insecticide monocrotophos. Diketenes react with substituted aromatic amines to acetoacetanilides, which are important precursors for many yellow, orange, and red azo dyes and azo pigments.

Exemplary for the synthesis of arylides by the reaction of diketenes with aromatic amines is:

Acetoacetanilid from diketene.svg

Aromatic diazonium coupling with arylides to form azo dyes, such as Pigment Yellow 74.

The industrial synthesis of the sweetener acesulfam-K is based on the reaction of diketene with sulfamic acid and cyclization by sulfur trioxide (SO3). [10]

Drugs made from Diketene include:

  1. Lercanidipine
  2. Manidipine
  3. Olaquindox
  4. Butoctamide
  5. Ketazolam
  6. Carboxin
  7. Ipramidil

Safety

Despite its high reactivity as an alkylating agent, and unlike analogue β-lactones propiolactone and β-butyrolactone, diketene is inactive as a carcinogen, possibly due to the instability of its DNA adducts. [11]

Related Research Articles

<span class="mw-page-title-main">Amine</span> Chemical compounds and groups containing nitrogen with a lone pair (:N)

In chemistry, amines are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Formally, amines are derivatives of ammonia (NH3, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines, trimethylamine, and aniline. Inorganic derivatives of ammonia are also called amines, such as monochloramine.

<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.

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

Acetoacetic acid is the organic compound with the formula CH3COCH2COOH. It is the simplest beta-keto acid, and like other members of this class, it is unstable. The methyl and ethyl esters, which are quite stable, are produced on a large scale industrially as precursors to dyes. Acetoacetic acid is a weak acid.

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.

The Friedel–Crafts reactions are a set of reactions developed by Charles Friedel and James Crafts in 1877 to attach substituents to an aromatic ring. Friedel–Crafts reactions are of two main types: alkylation reactions and acylation reactions. Both proceed by electrophilic aromatic substitution.

<span class="mw-page-title-main">Alkylation</span> Transfer of an alkyl group from one molecule to another

Alkylation is a chemical reaction that entails transfer of an alkyl group. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene. Alkylating agents are reagents for effecting alkylation. Alkyl groups can also be removed in a process known as dealkylation. Alkylating agents are often classified according to their nucleophilic or electrophilic character. In oil refining contexts, alkylation refers to a particular alkylation of isobutane with olefins. For upgrading of petroleum, alkylation produces a premium blending stock for gasoline. In medicine, alkylation of DNA is used in chemotherapy to damage the DNA of cancer cells. Alkylation is accomplished with the class of drugs called alkylating antineoplastic agents.

<span class="mw-page-title-main">Azo compound</span> Organic compounds with a diazenyl group (–N=N–)

Azo compounds are organic compounds bearing the functional group diazenyl.

Organochlorine chemistry is concerned with the properties of organochlorine compounds, or organochlorides, organic compounds that contain one or more carbon–chlorine bonds. The chloroalkane class includes common examples. The wide structural variety and divergent chemical properties of organochlorides lead to a broad range of names, applications, and properties. Organochlorine compounds have wide use in many applications, though some are of profound environmental concern, with TCDD being one of the most notorious.

<span class="mw-page-title-main">Triazine</span> Aromatic, heterocyclic compound

Triazines are a class of nitrogen-containing heterocycles. The parent molecules' molecular formula is C3H3N3. They exist in three isomeric forms, 1,3,5-triazines being common.

<span class="mw-page-title-main">Meldrum's acid</span> Chemical compound

Meldrum's acid or 2,2-dimethyl-1,3-dioxane-4,6-dione is an organic compound with formula C6H8O4. Its molecule has a heterocyclic core with four carbon and two oxygen atoms; the formula can also be written as [−O−(C 2)−O−(C=O)−(CH2)−(C=O)−].

<span class="mw-page-title-main">Azo dye</span> Class of organic compounds used as dye

Azo dyes are organic compounds bearing the functional group R−N=N−R′, in which R and R′ are usually aryl and substituted aryl groups. They are a commercially important family of azo compounds, i.e. compounds containing the C−N=N−C linkage. Azo dyes are synthetic dyes and do not occur naturally. Most azo dyes contain only one azo group but there are some that contain two or three azo groups, called "diazo dyes" and "triazo dyes" respectively. Azo dyes comprise 60–70% of all dyes used in food and textile industries. Azo dyes are widely used to treat textiles, leather articles, and some foods. Chemically related derivatives of azo dyes include azo pigments, which are insoluble in water and other solvents.

<span class="mw-page-title-main">Diazonium compound</span> Group of organonitrogen compounds

Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group [R−N+≡N]X where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide. The parent compound where R is hydrogen, is diazenylium.

In organic chemistry, an azo coupling is an reaction between a diazonium compound and another aromatic compound that produces an azo compound. In this electrophilic aromatic substitution reaction, the aryldiazonium cation is the electrophile, and the activated carbon, serves as a nucleophile. Classical coupling agents are phenols and naphthols. Usually the diazonium reagent attacks at the para position of the coupling agent. When the para position is occupied, coupling occurs at a ortho position, albeit at a slower rate.

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

The organic compound ethyl acetoacetate (EAA) is the ethyl ester of acetoacetic acid. It is a colorless liquid. It is widely used as a chemical intermediate in the production of a wide variety of compounds.

<span class="mw-page-title-main">Squaraine dye</span> Class of organic molecules

Squaraine dyes are a class of organic dyes showing intense fluorescence, typically in the red and near infrared region. They are characterized by their unique aromatic four membered ring system derived from squaric acid. Most squaraines are encumbered by nucleophilic attack of the central four membered ring, which is highly electron deficient. This encumbrance can be attenuated by the formation of a rotaxane around the dye to protect it from nucleophiles. They are currently used as sensors for ions and have recently, with the advent of protected squaraine derivatives, been exploited in biomedical imaging.

The reduction of nitro compounds are chemical reactions of wide interest in organic chemistry. The conversion can be effected by many reagents. The nitro group was one of the first functional groups to be reduced. Alkyl and aryl nitro compounds behave differently. Most useful is the reduction of aryl nitro compounds.

<span class="mw-page-title-main">Ethenone</span> Organic compound with the formula H2C=C=O

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.

Organobromine chemistry is the study of the synthesis and properties of organobromine compounds, also called organobromides, which are organic compounds that contain carbon bonded to bromine. The most pervasive is the naturally produced bromomethane.

The Danheiser benzannulation is a chemical reaction used in organic chemistry to generate highly substituted phenols in a single step. It is named after Rick L. Danheiser who developed the reaction.

<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. Beilstein E III/IV 17: 4297.
  2. 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.
  3. Susana Breda; Igor Reva; Rui Fausto (2012). "UV Induced Unimolecular Photochemistry of Diketene Isolated in Cryogenic Inert Matrices". J. Phys. Chem. A . 116 (9): 2131–2140. Bibcode:2012JPCA..116.2131B. doi:10.1021/jp211249k. PMID   22273010.
  4. Rafael Gómez-Bombarelli; Marina González-Pérez; María Teresa Pérez-Prior; José A. Manso; Emilio Calle; Julio Casado (2008). "Kinetic Study of the Neutral and Base Hydrolysis of Diketene". J. Phys. Org. Chem. 22 (5): 438–442. doi:10.1002/poc.1483.
  5. 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 ]
  6. Kiran Kumar Solingapuram Sai; Thomas M. Gilbert; Douglas A. Klumpp (2007). "Knorr Cyclizations and Distonic Superelectrophiles". J. Org. Chem. 72 (25): 9761–9764. doi:10.1021/jo7013092. PMID   17999519.
  7. Ashford's Dictionary of Industrial Chemicals, Third Edition, 2011, pages 3241-2.
  8. Hunger, K.; Herbst, W. (2012). "Pigments, Organic". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a20_371. ISBN   978-3527306732.
  9. Wolf S. Schultz: Sizing Agents in Fine Paper [ permanent dead link ] Retrieved 1 March 2012.
  10. EP 0218076 Process for the preparation of the non-toxic salts of 6-methyl-3,4-dihydro-1,2,3-oxathiazin-4-on-2,2-dioxide.
  11. Rafael Gómez-Bombarelli; Marina González-Pérez; María Teresa Pérez-Prior; José A. Manso; Emilio Calle; Julio Casado (2008). "Chemical Reactivity and Biological Activity of Diketene". Chem. Res. Toxicol. 21 (10): 1964–1969. doi:10.1021/tx800153j. PMID   18759502.