Everything about Propylene Oxide totally explained
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Propylene oxide is a highly toxic flammable
chemical compound. It is an
epoxide having a molecular formula C
3H
6O.
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.
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. 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.
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.
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.
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.
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Uses
Between 60 and 70% of all propylene oxide is consumed making
polyether polyols for use in making
polyurethane plastics. 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.
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.
Further Information
Get more info on 'Propylene Oxide'.
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