Epichlorohydrin

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(±)-Epichlorohydrin[1]
Epichlorohydrin
Ball-and-stick model of the epichlorohydrin molecule
Identifiers
CAS number 106-89-8 YesY
PubChem 7835
ChemSpider 13837112 YesY
UNII 08OOR508C0 YesY
KEGG C14449 YesY
ChEBI CHEBI:37144 YesY
Jmol-3D images Image 1
Properties
Molecular formula C3H5ClO
Molar mass 92.52 g/mol
Appearance colorless liquid
Odor garlic-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)
Solubility in water reacts
Hazards
MSDS External MSDS
EU classification Toxic T
NFPA 704
Flammability code 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g., gasoline) Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorus Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point 32 °C (90 °F; 305 K)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

Epichlorohydrin (abbreviated ECH) is an organochlorine compound and an epoxide. Despite its name, it is not a chlorohydrin. It is a colorless liquid with a pungent, garlic-like odor, moderately soluble in water, but miscible with most polar organic solvents.[2] 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[edit]

Epichlorohydrin is manufactured from allyl chloride in two steps, beginning with the addition of hypochlorous acid, which affords a mixture of two alcohols:[3]

CH2=CHCH2Cl + HOCl → HOCH2CHClCH2Cl and, or ClCH2CH(OH)CH2Cl
Epichlorohydrin-manufacture-step1-2D-skeletal.png

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

HOCH2CHClCH2Cl and, or ClCH2CH(OH)CH2Cl + NaOH → CH2CHOCH2Cl + NaCl + H2O
Epichlorohydrin-manufacture-step2-2D-skeletal.png

In this way, more than 800,000 tons (1997) of epichlorohydrin are produced annually.[4]

From glycerol[edit]

Glycerol is a co-product of biodiesel produced on a large scale. The conversion of glycerol into other building block chemicals is of great interest because glycerol is otherwise hard to dispose of. Dow and Solvay are building glycerol-to-epichlorohydrin (GTE) plants in Shanghai and Thailand, respectively.[5] 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.[6]

Applications[edit]

Glycerol and epoxy resins synthesis[edit]

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.[7]

See also: § Production

Minor and niche applications[edit]

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.[8] 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.[9]

Polymers made from epichlorohydrin, e.g., polyamide-epichlorohydrin resins, are used in paper reinforcement and, such as in the food industry to manufacture tea bags, coffee filters, and sausage/salami casings as well as with water purification.[10]

An important biochemical application of epichlorohydrin is its use as crosslinking agent for the production of Sephadex size-exclusion chromatographic resins from dextrans.[11]

Safety[edit]

Epichlorohydrin is classified by several international health research agencies and groups as a probable or likely human carcinogen in humans.[12][13][14] Prolonged oral consumption of high levels of epichlorohydrin could result in stomach problems and an increased risk of cancer.[15] Occupational exposure to epichlorohydrin via inhalation could result in lung irritation and an increased risk of lung cancer.[16]

See also[edit]

References[edit]

  1. ^ Merck Index, 12th Edition, 3648.
  2. ^ "EPA consumer factsheet". Epa.gov. Retrieved 2011-12-02. 
  3. ^ Guenter Sienel; Robert Rieth; Kenneth T. Rowbottom (2005), "Epoxides", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a09_531 
  4. ^ Ludger Krähling; Jürgen Krey; Gerald Jakobson; Johann Grolig; Leopold Miksche (2005), "Allyl Compounds", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a01_425 
  5. ^ Doris de Guzman (2011-01-20). "Growing glycerine-to-ECH plants". ICIS Green Chemicals. 
  6. ^ Bell, Bruce M.; Briggs, John R.; Campbell, Robert M.; Chambers, Susanne M.; Gaarenstroom, Phil D.; Hippler, Jeffrey G.; Hook, Bruce D.; Kearns, Kenneth et al. (2008). "Glycerin as a Renewable Feedstock for Epichlorohydrin Production. The GTE Process" (full text reprint). CLEAN - Soil, Air, Water 36 (8): 657. doi:10.1002/clen.200800067. 
  7. ^ "OPTIM Synthetic Glycerine". Retrieved 2012-03-05. 
  8. ^ Gould, R.F. Advanced Propellant Chemistry, ACS Chemistry Series 54, 1966
  9. ^ "Suburban Water Testing Labs:Epichlorohydrin Fact Sheet". H2otest.com. Retrieved 2011-12-02. 
  10. ^ "Government of Canada Chemical Substances: Oxirane,(chloromethyl)-(Epichlorohydrin) CAS Registry Number 106-89-8". Retrieved 2013-05-07. 
  11. ^ "GE Healthcare Life Sciences - Instructions for Sephadex Media". .gelifesciences.com. Retrieved 2011-12-02. 
  12. ^ "EPA Integrated Risk Information System: Epichlorohydrin (CASRN 106-89-8)". Retrieved 2013-05-07. 
  13. ^ "Government of Canada: Screening Assessment for Epichlorohydrin". Retrieved 2013-05-07. 
  14. ^ "NIOSH Pocket Guide to Chemical Hazards - Epichlorohydrin". Retrieved 2013-09-20. 
  15. ^ "Basic Information about Epichlorohydrin in Drinking Water". Retrieved 2013-05-07. 
  16. ^ "Government of Canada: Screening Assessment for Epichlorohydrin". Retrieved 2013-05-07.