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Tetrafluoroethylene
 
 
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Tetrafluoroethylene (TFE) is a chemical compound
Chemical compound

A chemical compound is a Chemical substance consisting of two or more different chemical element Chemical bond together in a fixed mass ratio that can be split into simpler substances....
 with the formula C2F4. It is the simplest unsaturated
Unsaturated compound

In organic chemistry, an unsaturated compound is a chemical compound that contains carbon-carbon double bonds or triple bonds such as in alkenes or alkynes....
 fluorocarbon
Fluorocarbon

Fluorocarbons, sometimes referred to as perfluorocarbons, are organofluorine compounds that contain only carbon and fluorine bonded together in strong carbon?fluorine bonds....
. This gaseous species is used primarily in the industrial preparation of polymer
Polymer

A polymer is a large molecule composed of repeating structural units typically connected by covalent chemical bonds. While polymer in popular usage suggests plastic, the term actually refers to a large class of natural and synthetic materials with a variety of properties....
s. In organic chemistry, tetrafluoroethylene is a potent dienophile.

afluoroethylene is a colourless, odourless gas. Like all unsaturated fluorocarbons it is susceptible to nucleophilic attack.






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Tetrafluoroethylene (TFE) is a chemical compound
Chemical compound

A chemical compound is a Chemical substance consisting of two or more different chemical element Chemical bond together in a fixed mass ratio that can be split into simpler substances....
 with the formula C2F4. It is the simplest unsaturated
Unsaturated compound

In organic chemistry, an unsaturated compound is a chemical compound that contains carbon-carbon double bonds or triple bonds such as in alkenes or alkynes....
 fluorocarbon
Fluorocarbon

Fluorocarbons, sometimes referred to as perfluorocarbons, are organofluorine compounds that contain only carbon and fluorine bonded together in strong carbon?fluorine bonds....
. This gaseous species is used primarily in the industrial preparation of polymer
Polymer

A polymer is a large molecule composed of repeating structural units typically connected by covalent chemical bonds. While polymer in popular usage suggests plastic, the term actually refers to a large class of natural and synthetic materials with a variety of properties....
s. In organic chemistry, tetrafluoroethylene is a potent dienophile.

Properties

Tetrafluoroethylene is a colourless, odourless gas. Like all unsaturated fluorocarbons it is susceptible to nucleophilic attack. It is unstable towards decomposition to C and CF4 and prone to form explosive peroxides in contact with air.

Industrial use

Polymerization of tetrafluoroethylene produces polytetrafluoroethylene
Polytetrafluoroethylene

In chemistry, poly or poly is a synthetic fluoropolymer which finds numerous applications. PTFE is most well known by the DuPont brand name Teflon....
 (PTFE) polymers such as Teflon and Fluon. PTFE is one of the two fluorocarbon resins composed wholly of fluorine and carbon. The other resin composed purely of carbon and fluorine is the copolymer of TFE with typically 6-9% hexafluoropropene (HFP), which is known as FEP (fluorinated ethylene propylene copolymer). TFE is also used in the preparation of numerous copolymers that also include hydrogen and/or oxygen, including both fluoroplastics and fluoroelastomers. Typical TFE-based fluoroplastics include ETFE, the alternating 1:1 copolymer with ethylene, and PFA, which is a random copolymer similar to FEP but with a minor amount of a perfluoroalkyl vinyl ether (PAVE)rather than HFP. DuPont uses primarily perfluoro(methylvinylether), whereas Daikin uses primarily perfluoro(propylvinylether) in manufacturing PFA. There are numerous other fluoropolymers that contain TFE, but usually not at greater than 50% by weight.

Manufacture

TFE is manufactured from chloroform
Chloroform

Chloroform, also known as trichloromethane and methyl trichloride, is a chemical compound with chemical formula CarbonHydrogenChlorine3....
. Chloroform is fluorinated by reaction with hydrogen fluoride
Hydrogen fluoride

Hydrogen fluoride is a chemical compound with the chemical formula HF. It is the principal industrial source of fluorine, often in the aqueous form as hydrofluoric acid, and thus is the precursor to many important compounds including pharmaceuticals and polymers ....
 to produce chlorodifluoromethane
Chlorodifluoromethane

Chlorodifluoromethane or difluoromonochloromethane is a hydrochlorofluorocarbon . It is better known under its code names of HCFC-22, R-22, Genetron 22 or Freon 22, and is commonly used in air conditioning applications, such as residential split systems in the US, rooftop units and window air conditioners....
 (R-22). Pyrolysis of chlorodifluoromethane then yields TFE, with difluorocarbene as an intermediate.
CHCl3 + 2 HF ? CHClF2 + 2 HCl
2 CHClF2 ? C2F4 + 2 HCl


The reverse reaction – vacuum pyrolysis of PTFE at 600–650 °C in a quartz vessel
Fused quartz

Fused quartz and fused silica are types of glass containing primarily silica in amorphous solid form. They are manufactured using several different processes....
 – is a convenient laboratory synthesis of TFE. The PTFE polymer cracks
Cracking (chemistry)

In petroleum geology and chemistry, cracking is the process whereby complex organic compound molecules such as kerogens or heavy hydrocarbons are broken down into simpler molecules by the breaking of carbon-carbon chemical bond in the precursors....
, and at a pressure below 5 torr exclusively C2F4 is obtained. At higher pressures the product mixture contains hexafluoropropylene
Hexafluoropropylene

Hexafluoropropylene in a compound with the formula C3F6. It is a fluorocarbon alkene in which all of the hydrogen atoms in propylene are replaced by fluorine atoms....
 and octafluorocyclobutane.

Safety

TFE is an alkylating agent, albeit a weak one, and as such is expected to be carcinogenic. LD50(rat, inhalation) = 40000 ppm.. The compound is best handled diluted with an inert gas, as localized heating can provoke explosive decomposition to C and CF4. When working with TFE oxygen must be scrupulously excluded when handling the compound, as it catalyzes autopolymerization, which can take place with great force.

There is also a danger of explosion when working with TFE, from adiabatic compression. If pressurised TFE is allowed into a vessel/pipework at a lower pressure the heat generated from compression may be sufficient to ignite the TFE, causing explosion/explosive decomposition.

In industry pipework is flushed with pressurised nitrogen, before the introduction of TFE, both to exclude oxygen and to avoid adiabatic compression.

See also

  • Tetrachloroethylene
    Tetrachloroethylene

    Tetrachloroethylene, also known under its systematic name tetrachloroethene and as perchloroethylene, perchloroethene, perc, and PCE, is a chlorocarbon with the formula Cl2C=CCl2....
  • 1,1,1,2-Tetrafluoroethane
    1,1,1,2-Tetrafluoroethane

    1,1,1,2-Tetrafluoroethane, also called simply tetrafluoroethane, R-134a, Genetron 134a, Suva 134a or HFC-134a, is a haloalkane refrigerant with thermodynamic properties similar to dichlorodifluoromethane , but without its ozone depletion potential....


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