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A ketene is an organic compound
Organic compound

An organic compound is any member of a large class of chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of compounds such as carbonates, simple oxides of carbon and cyanides, as well as the allotropes of carbon, are considered Inorganic compound....
 of the form R2C=C=O. Hermann Staudinger
Hermann Staudinger

Hermann Staudinger was a German chemist who demonstrated the existence of macromolecules which he characterized as polymers. For this work he received the 1953 Nobel Prize in Chemistry....
 pioneered the research of ketenes. Ketene also refers to ethenone, the specific compound of this class in which both Rs are hydrogen.

none is colourless and has a sharp odour, and exposure to concentrated levels causes humans to experience irritation of body parts such as the eye
Eye

Eyes are Organ that detect light, and send signals along the optic nerve to the visual system and other areas of the brain. Complex optical systems with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system....
, nose
Nose

Anatomically, a nose is a protuberance in vertebrates that houses the nostrils, or nares, which admit and expel air for Respiration in conjunction with the mouth....
, throat
Throat

In anatomy, the throat is the anterior part of the neck, in front of the vertebrae. It consists of the pharynx and larynx. An important feature of the throat is the epiglottis, a flap which separates the esophagus from the vertebrate trachea and prevents inhalation of food or drink....
, and lung
Lung

The lung is the essential respiration organ in air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located in the chest on either side of the heart....
.






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Cetene2
Ketene 3d Vdw
A ketene is an organic compound
Organic compound

An organic compound is any member of a large class of chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of compounds such as carbonates, simple oxides of carbon and cyanides, as well as the allotropes of carbon, are considered Inorganic compound....
 of the form R2C=C=O. Hermann Staudinger
Hermann Staudinger

Hermann Staudinger was a German chemist who demonstrated the existence of macromolecules which he characterized as polymers. For this work he received the 1953 Nobel Prize in Chemistry....
 pioneered the research of ketenes. Ketene also refers to ethenone, the specific compound of this class in which both Rs are hydrogen.

Properties of ethenone

Ethenone is colourless and has a sharp odour, and exposure to concentrated levels causes humans to experience irritation of body parts such as the eye
Eye

Eyes are Organ that detect light, and send signals along the optic nerve to the visual system and other areas of the brain. Complex optical systems with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system....
, nose
Nose

Anatomically, a nose is a protuberance in vertebrates that houses the nostrils, or nares, which admit and expel air for Respiration in conjunction with the mouth....
, throat
Throat

In anatomy, the throat is the anterior part of the neck, in front of the vertebrae. It consists of the pharynx and larynx. An important feature of the throat is the epiglottis, a flap which separates the esophagus from the vertebrate trachea and prevents inhalation of food or drink....
, and lung
Lung

The lung is the essential respiration organ in air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located in the chest on either side of the heart....
. Pulmonary edema
Pulmonary edema

Pulmonary edema , or oedema , is swelling and/or fluid accumulation in the lungs. It leads to impaired gas exchange and may cause respiratory failure....
 has also been noted if these levels are experienced for an extended period of time. It has a melting
Melting

Melting is a process that results in the phase change of a substance from a solid to a liquid. The internal energy of a solid substance is increased to a specific temperature at which it changes to the liquid phase....
 point of -150.5 °C (-239 °F) and a boiling
Boiling

Boiling, a type of phase transition, is the rapid vaporization of a liquid, which typically occurs when a liquid is heated to its boiling point, the temperature at which the vapor pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding environmental pressure....
 point of -56.1 °C (-69 °F).

Formation

  • Ketenes can be prepared from acyl chloride
    Acyl chloride

    In organic chemistry, an acyl chloride is an organic compound which is a reactive derivative of a carboxylic acid. As part of its molecular structure, an acyl chloride has the reactive functional group -Carbonyl-Chlorine and has the general formula RCOCl, where R is an organic radical group....
    s by an elimination reaction
    Elimination reaction

    An elimination reaction is a type of organic reaction in which two substituents are removed from a molecule in either a one or two-step mechanism ....
     in which HCl is lost.
Mecanisme De La Formation Des Cetenes
:A base, usually triethylamine
Triethylamine

Triethylamine is the chemical compound with the chemical formula N3, commonly abbreviated ethyl group3N or TEA. It is a commonly encountered in organic synthesis probably because it is the simplest symmetrically trisubstituted amine, i.e....
, removes the acidic proton alpha to the carbonyl group, inducing the formation of the carbon-carbon double bond and the loss of chloride ion.
  • Ketenes are formed in the Wolff rearrangement
    Wolff rearrangement

    The Wolff rearrangement is a rearrangement reaction converting a a-diazo-ketone into a ketene. This reaction was first reported by Ludwig Wolff in 1912....
     from a-diazoketones
  • Phenylacetic acid in the presence of base will lose water to produce phenylketene due to the high acidity of the alpha proton.
  • Ethenone (CH2=C=O) can be prepared in the laboratory by pyrolysis
    Pyrolysis

    Pyrolysis is the chemical decomposition of a condensed substance by heating. The word is coined from the Greek language-derived morphemes pyro "fire" and lysys "decomposition"....
     of acetone
    Acetone

    Acetone is the organic compound with the chemical formula OC2. This colorless, mobile, flammable liquid is the simplest example of the ketones....
     vapor:


CH3-CO-CH3 + Δ ? CH2=C=O + CH4


Reactions

Ketene is very reactive, tending to react with nucleophiles to form an acetyl group. For example, ketene reacts with acetic acid
Acetic acid

Acetic acid, CH3COOH, also known as ethanoic acid, is an organic acid which gives vinegar its sour taste and pungent smell. Pure, water-free acetic acid is a colourless liquid that absorbs water from the environment , and freezes at 16.7 Celsius to a colourless crystalline solid....
 to form acetic anhydride
Acetic anhydride

Acetic anhydride is the chemical compound with the chemical formula 2O. Commonly abbreviated Acetyl2O, it is one of the simplest acid anhydrides and is a widely used reagent in organic synthesis....
. It will also react with itself via a [2+2] cycloaddition
Cycloaddition

A cycloaddition is a pericyclic chemical reaction, in which two pi bond are lost and two sigma bond are gained. The resulting reaction is a cyclization reaction....
 to form cyclic dimer
Dimer

File:Carboxylic acid dimers.pngA dimer is a chemical or biological entity consisting of two identical subunits called monomers, which are held together by either intramolecular forces or weaker intermolecular forces....
s known as diketene
Diketene

Diketene is an organic compound formed by dimerization of ketene. Diketene is a member of the oxetane family. It is used as a chemical reagent in organic chemistry....
s. Ketenes also participate in other cycloadditions and will also undergo [2+2] cycloaddition reactions with electron-rich alkynes to form cyclobutenones, or carbonyl
Carbonyl

In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double bond to an oxygen atom : C=O.The term carbonyl can also refer to carbon monoxide as a ligand in an inorganic or organometallic complex ; in this situation, carbon is triple-bonded to oxygen : C=O....
 groups to form beta-lactones.

Reactions between diol
Diol

A diol or glycol is a chemical compound containing two hydroxyl groups Vicinal diols have hydroxyl groups attached to adjacent atoms. Examples of vicinal diol compounds are ethylene glycol and propylene glycol....
s (HO-R-OH) and bis-ketenes (O=C=CH-R'-CH=C=O) yield polyesters with a repeat unit of (-O-R-O-CO-R'-CO-).

See also

  • Ynolate
    Ynolate

    Ynolates are chemical compounds with a negatively charged oxygen attached to an alkyne functionality. They were first synthesized in 1975 by Sch?llkopf and Hoppe via the N-Butyllithium fragmentation of 3,4-diphenylisoxazole....