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Epichlorohydrin

Epichlorohydrin
(Click here for a model of a molecule of Epichlorohydrin)

News about Epichlorohydrin



Epichlorohydrin is an organochlorine compound and an epoxide. This is a colorless liquid with a pungent, garlic-like odor, insoluble in water, but miscible with most polar molecule|polar Organic compound|organic solvents.Epichlorohydrin is a highly reactive compound and is used in the production of glycerol, plastics, epoxy glues and Epoxy resin], and elastomers. In contact with water, epichlorohydrin hydrolyzes to 3-MCPD, a carcinogen found in food.

Production
Epichlorohydrin is manufactured from allyl chloride in two steps, beginning with the hydrochlorination using hypochlorous acid, which affords a mixture of two alcohols:
CH2=CHCH2Cl + HOCl → HOCH2CHClCH2Cl and, or ClCH2CH(OH)CH2Cl

In the second step, this mixture is treated with base to give the epoxide:
HOCH2CHClCH2Cl and, or ClCH2CH(OH)CH2Cl + NaOH → CH2CHOCH2Cl + NaCl + H2O

In this way, more than 700,000 tons of epichlorohydrin are produced annually. Ludger Krähling, Jürgen Krey, Gerald Jakobson, Johann Grolig, Leopold Miksche “Allyl compounds” in Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH, Weinheim, 2005. Published online: 15 June 2000.

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 In fact, ways to perform the reverse process are now being researched, to produce epichlorohydrin from the now less valuable natural glycerol, a process now commercialised by Solvay SA with a commercial demo site producing 10 000 tons annually.

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.The epichlorohydrin is reacted with an alkali nitrate, such as sodium nitrate, producing glycidyl nitrate and alkali chloride. It used as a solvent for cellulose, resins and paints and it has found use as an insect fumigant. used in paper reinforcement (used for instance in the food industry to manufacture tea bags, coffee filters, and sausage/salami casings and water purification.
An important biochemical application of epichlorohydrin is its use as crosslinking agent for the production of Sephadex size-exclusion chromatographic resins from dextrans

Safety
Epichlorohydrin is irritating and moderately toxic as well as carcinogenic.
See also

References