Epichlorohydrin

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(±)-Epichlorohydrin[1]
Epichlorohydrin
The rear section of ball-and-stick model of the epichlorohydrin molecule
Ball-and-stick model of the epichlorohydrin molecule
Names
IUPAC name
chloromethyloxirane
Other names
epichlorohydrin
1-chloro-2,3-epoxypropane
γ-chloropropylene oxide
glycidyl chloride
Identifiers
106-89-8 YesY
ChEBI CHEBI:37144 YesY
ChemSpider 13837112 YesY
Jmol 3D model Interactive image
KEGG C14449 YesY
PubChem 7835
UNII 08OOR508C0 YesY
  • InChI=1S/C3H5ClO/c4-1-3-2-5-3/h3H,1-2H2 YesY
    Key: BRLQWZUYTZBJKN-UHFFFAOYSA-N YesY
  • InChI=1/C3H5ClO/c4-1-3-2-5-3/h3H,1-2H2
    Key: BRLQWZUYTZBJKN-UHFFFAOYAY
  • ClCC1CO1
Properties
C3H5ClO
Molar mass 92.52 g/mol
Appearance colorless liquid
Odor garlic-like, chloroform-like
Density 1.1812 g/cm3
Melting point −25.6 °C (−14.1 °F; 247.6 K)
Boiling point 117.9 °C (244.2 °F; 391.0 K)
7% (20°C)[2]
Vapor pressure 13 mmHg (20°C)[2]
Vapor pressure {{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY verify (what is YesYN ?)
Infobox references

Epichlorohydrin (abbreviated ECH) is an organochlorine compound and an epoxide. Despite its name, it is not a halohydrin. It is a colorless liquid with a pungent, garlic-like odor, moderately soluble in water, but miscible with most polar organic solvents.[3] It is a chiral molecule generally existing as a racemic mixture of right-handed and left-handed enantiomers. Epichlorohydrin is a highly reactive compound and is used in the production of glycerol, plastics, epoxy glues and resins, and elastomers. In contact with water, epichlorohydrin hydrolyzes to 3-MCPD, a carcinogen found in food.

Production

Epichlorohydrin was first described in 1848 by Marcellin Berthelot. The compound was isolated during studies on reactions between glycerol and gaseous hydrogen chloride.[4]

Epichlorohydrin is manufactured from allyl chloride in two steps, beginning with the addition of hypochlorous acid, which affords a mixture of two alcohols:[5][6]

CH2=CHCH2Cl + HOCl → HOCH2CHClCH2Cl and, or ClCH2CH(OH)CH2Cl

In the second step, this mixture is treated with base to give the epoxide:

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In this way, more than 800,000 tons (1997) of epichlorohydrin are produced annually.[7]

From glycerol

Glycerol is a co-product of biodiesel produced on a large scale. The conversion of glycerol into other building block chemicals is of interest because glycerol is otherwise hard to dispose of. Dow and Solvay are building glycerol-to-epichlorohydrin (GTE) plants in Shanghai and Thailand, respectively.[8] In Dow's process, glycerol is dichlorinated with hydrogen chloride with the help of a carboxylic acid catalyst. The mixture of dichlorohydroxypropanes is treated with base to form epichlorohydrin.[9]

Applications

Glycerol and epoxy resins synthesis

Epichlorohydrin is mainly converted to bisphenol A diglycidyl ether, a building block in the manufacture of epoxy resins. It is also a precursor to monomers for other resins and polymers. Another usage is the conversion to synthetic glycerol:

CH2CHOCH2Cl + 2 H2O → HOCH2CH(OH)CH2(OH) + HCl

However, the rapid increase in biodiesel production, where glycerol is a waste product, has led to a glut of glycerol on the market, rendering this process uneconomic for the mass market. Synthetic glycerol is now used only in sensitive pharmaceutical, technical and personal care applications where quality standards are very high.[10]

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See also: § Production

Minor and niche applications

Epichlorohydrin is a versatile precursor in the synthesis of many organic compounds. For example, it is converted to glycidyl nitrate, an energetic binder used in explosive and propellant compositions.[11] The epichlorohydrin is reacted with an alkali nitrate, such as sodium nitrate, producing glycidyl nitrate and alkali chloride. It is used as a solvent for cellulose, resins, and paints, and it has found use as an insect fumigant.[12]

Polymers made from epichlorohydrin, e.g., polyamide-epichlorohydrin resins, are used in paper reinforcement and in the food industry to manufacture tea bags, coffee filters, and sausage/salami casings as well as with water purification.[13]

An important biochemical application of epichlorohydrin is its use as crosslinking agent for the production of Sephadex size-exclusion chromatographic resins from dextrans.[14]

Safety

Epichlorohydrin is classified by several international health research agencies and groups as a probable or likely human carcinogen in humans.[15][16][17] Prolonged oral consumption of high levels of epichlorohydrin could result in stomach problems and an increased risk of cancer.[18] Occupational exposure to epichlorohydrin via inhalation could result in lung irritation and an increased risk of lung cancer.[19]

See also

References

  1. ↑ Merck Index, 12th Edition, 3648.
  2. ↑ 2.0 2.1 Cite error: Invalid <ref> tag; no text was provided for refs named PGCH
  3. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ Géza Braun "Epichlorohydrin and Epibromohydrin" Organic Syntheses,1936, Vol. 16, p.30. doi:10.15227/orgsyn.016.0030
  6. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  9. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  11. ↑ Gould, R.F. Advanced Propellant Chemistry, ACS Chemistry Series 54, 1966
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  14. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  15. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  16. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  17. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  18. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  19. ↑ Lua error in package.lua at line 80: module 'strict' not found.

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