Epichlorohydrin

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
(±)-Epichlorohydrin[1]
Epichlorohydrin skeletal structure
R-Epichlorohydrin-calculated-MP2-3D-balls.png
(R)-Epichlorohydrin
S-Epichlorohydrin-calculated-MP2-3D-balls.png
(S)-Epichlorohydrin
Names
Preferred IUPAC name
2-(Chloromethyl)oxirane
Other names
(Chloromethyl)oxirane
Epichlorohydrin
1-Chloro-2,3-epoxypropane
γ-Chloropropylene oxide
Glycidyl chloride
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.003.128
KEGG
UNII
Properties
C3H5ClO
Molar mass 92.52 g/mol
Appearance colorless liquid
Odor garlic or 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]
Hazards
Safety data sheet External MSDS
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., gasolineHealth code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gasReactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorusSpecial hazards (white): no codeNFPA 704 four-colored diamond
3
3
2
Flash point 32 °C (90 °F; 305 K)
Explosive limits 3.8%-21%[2]
Lethal dose or concentration (LD, LC):
3617 ppm (rat, 1 hr)
2165 ppm (rat, 1 hr)
250 ppm (rat, 8 hr)
244 ppm (rat, 8 hr)
360 ppm (rat, 6 hr)[3]
250 ppm (rat, 4 hr)[3]
US health exposure limits (NIOSH):
PEL (Permissible)
TWA 5 ppm (19 mg/m3) [skin][2]
REL (Recommended)
Carcinogen[2]
IDLH (Immediate danger)
Ca [75 ppm][2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☑Y verify (what is ☑Y☒N ?)
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.[4] It is a chiral molecule generally existing as a racemic mixture of right-handed and left-handed enantiomers. Epichlorohydrin is a highly reactive electrophilic compound and is used in the production of glycerol, plastics, epoxy glues and resins, and elastomers.

Production[edit]

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

Epichlorohydrin-manufacture-step1-2D-skeletal.png

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

Epichlorohydrin-manufacture-step2-2D-skeletal.png

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

Glycerol routes[edit]

Epichlorohydrin was first described in 1848 by Marcellin Berthelot. The compound was isolated during studies on reactions between glycerol and gaseous hydrogen chloride.[8]

Reminiscent of Berthelot's experiment, glycerol-to-epichlorohydrin (GTE) plants have been commercialized. This technology capitalizes on the availability of cheap glycerol from biofuels processing.[9] In the process developed Dow Chemical, glycerol is undergoes two substitution reactions when treated with hydrogen chloride in the presence of a carboxylic acid catalyst. This is the same intermediate formed in the allyl chloride/hypochlorous acid process, and is likewise then treated with base to form epichlorohydrin.[10]

GTE-Prozess.svg

Other routes[edit]

Routes that involve fewer chlorinated intermediates have continued to attract interest. One such process entails epoxidation of allyl chloride.[11]

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.[12] It is also a precursor to monomers for other resins and polymers. Another usage is the conversion to synthetic glycerol. 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 uneconomical. Synthetic glycerol is now used only in sensitive pharmaceutical, technical and personal care applications where quality standards are very high.[13]

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.[14] 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.[15]

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.[16]

An important biochemical application of epichlorohydrin is its use as crosslinking agent for the production of Sephadex size-exclusion chromatographic resins from dextrans.[17]

Safety[edit]

Epichlorohydrin is classified by several international health research agencies and groups as a probable or likely carcinogen in humans.[18][19][20] Prolonged oral consumption of high levels of epichlorohydrin could result in stomach problems and an increased risk of cancer.[21] Occupational exposure to epichlorohydrin via inhalation could result in lung irritation and an increased risk of lung cancer.[22]

References[edit]

  1. ^ Merck Index, 12th Edition, 3648.
  2. ^ a b c d e f "NIOSH Pocket Guide to Chemical Hazards #0254". National Institute for Occupational Safety and Health (NIOSH). 
  3. ^ a b "Epichlorohydrin". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH). 
  4. ^ "EPA consumer factsheet". Epa.gov. Retrieved 2011-12-02. 
  5. ^ Braun, G. (1936). "Epichlorohydrin and Epybromohydrin". Organic Syntheses. 16: 30. doi:10.15227/orgsyn.016.0030. 
  6. ^ Guenter Sienel; Robert Rieth; Kenneth T. Rowbottom (2005), "Epoxides", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a09_531 
  7. ^ 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 
  8. ^ Berthelot, Marcellin (1854). "Sur les combinaisons de la glycérine avec les acides et sur la synthèse des principes immédiats des graisses animaux". Ann. Chim. Phys. Série 3. 41: 216–319. 
  9. ^ Doris de Guzman (2011-01-20). "Growing glycerine-to-ECH plants". ICIS Green Chemicals. 
  10. ^ 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. 
  11. ^ Jun Li, Gongda Zhao, Shuang Gao, Ying Lv, Jian Li, and Zuwei Xi (2006). "Epoxidation of Allyl Chloride to Epichlorohydrin by a Reversible Supported Catalyst with H2O2 under Solvent-Free Conditions". Org. Process Res. Dev. 10: 876–880. doi:10.1021/op060108k. 
  12. ^ Pham, Ha Q.; Marks, Maurice J. (2012). "Epoxy Resins". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a09_547.pub2. 
  13. ^ "OPTIM Synthetic Glycerine". Retrieved 2012-03-05. 
  14. ^ Gould, R.F. Advanced Propellant Chemistry, ACS Chemistry Series 54, 1966
  15. ^ "Suburban Water Testing Labs:Epichlorohydrin Fact Sheet". H2otest.com. Retrieved 2011-12-02. 
  16. ^ "Government of Canada Chemical Substances: Oxirane,(chloromethyl)-(Epichlorohydrin) CAS Registry Number 106-89-8". Retrieved 2013-05-07. 
  17. ^ "GE Healthcare Life Sciences - Instructions for Sephadex Media". .gelifesciences.com. Retrieved 2011-12-02. 
  18. ^ "EPA Integrated Risk Information System: Epichlorohydrin (CASRN 106-89-8)". Retrieved 2013-05-07. 
  19. ^ "Government of Canada: Screening Assessment for Epichlorohydrin". Retrieved 2013-05-07. 
  20. ^ "NIOSH Pocket Guide to Chemical Hazards - Epichlorohydrin". Retrieved 2013-09-20. 
  21. ^ "Basic Information about Epichlorohydrin in Drinking Water". Retrieved 2013-05-07. 
  22. ^ "Government of Canada: Screening Assessment for Epichlorohydrin". Retrieved 2013-05-07.