Propylene oxide

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Propylene oxide
IUPAC name epoxypropane
Other names propylene oxide, epoxypropane, propylene epoxide, 1,2-propylene oxide, methyl oxirane, 1,2-epoxypropane, propene oxide, methyl ethylene oxide, methylethylene oxide
Identifiers
CAS number [75-56-9]
EINECS number 200-897-2
SMILES CC1CO1
Properties
Molecular formula C3H6O
Molar mass 58.08 g mol−1
Appearance colorless liquid
Density 0.830
Melting point

−112 °C
Boiling point

34 °C
Solubility in water appreciable
Hazards
NFPA 704
4
3
2
 
Flash point −37 °C
Autoignition
temperature		 747 °C
Explosive limits 2.1 - 37%
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Propylene oxide is a highly toxic flammable chemical compound. It is an epoxide having a molecular formula C3H6O.

Propylene oxide has a single chiral center, and thus exists as a pair of enantiomers. The material commonly available is a racemic mixture of the two enantiomers.

Its major industrial application is as a monomer for the production of polyether polyols for use in making polyurethane plastics.

Contents

[edit] Production

Industrial production of propylene oxide is mainly from co-oxidation of propylene with other chemicals.

In 2005, about half of the world production was through chlorohydrin technology (the first one of the above), one third from PO/SM technology (the third one), and the other from PO/TBA technology (the second one). The above technologies create additional side products.

In April 2003, Sumitomo Chemical commercialised the first PO-only plant in Japan, which produces propylene oxide from oxidation of cumene without significant production of other products.[1] This is a variant of the POSM process (third above) that uses cumene instead of ethylbenzene and recycles the coproducts via dehydration and hydrogenation back to cumene.

In the new HPPO-Process recently developed by BASF and Dow Chemical propylene is oxidized with hydrogen peroxide:

C3H6 + H2O2 → C3H6O + H2O

In this process no side products other than water are created. The first technical plant is currently being built in Antwerp and due to begin production in 2008.

[edit] Properties

Propylene oxide degrades into propylene glycol in the presence of water, a process which is accelerated by the presence of acid or base. Propylene oxide is a probable human carcinogen.[2]

Propylene oxide was accidentally found to be a very strong oxidizer. The discovery was made accidentally at SUNY Stony Brook when propylene oxide accidentally leaked onto a PVC pipe under pressure and caused the PVC piping to liquify. More research is being done in this area.

[edit] Chirality

Propylene oxide is a chiral compound due to the presence of an asymmetrical carbon atom in the oxirane cycle. Industrial propylene oxide is a racemic mixture.[1]

[edit] Uses

Between 60 and 70% of all propylene oxide is consumed making polyether polyols for use in making polyurethane plastics. [3] Propylene oxide is also used in the production of propylene glycol (using about 20% of propylene oxide), polypropylene glycol, propylene glycols ethers and propylene carbonate.

The United States Food & Drug Administration has approved its use to pasteurize raw almonds beginning on September 1, 2007 in response to several incidences of contamination by salmonella in commercial orchards.[4]

It was once used as a racing fuel, but that usage is now prohibited under the US NHRA rules for safety reasons. It is also used in thermobaric weapons, and microbial fumigation.

[edit] References

  1. ^ Summary of Sumitomo process from Nexant Reports. Retrieved on 2007-09-18.
  2. ^ Safety data for propylene oxide.
  3. ^ Usage of proplyene oxide, from Dow Chemical. Retrieved on 2007-09-10.
  4. ^ Agricultural Marketing Service, USDA (30 March 2007). "Almonds Grown in California; Outgoing Quality Control Requirements". Federal Register vol. 72 (no. 61): pp. 15,021–15,036. 

[edit] External links