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| Propylene oxide | |
|---|---|
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| 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 | |
| SMILES |
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| 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 | |
| MSDS | Oxford MSDS |
| 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 references |
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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 |
Production
Industrial production of propylene oxide is mainly from co-oxidation of propylene with other chemicals.
- Propylene + Chlorine + Lime (chlorine absorber) → Propylene oxide + Calcium Chloride (intermediates are propylene chlorohydrines, a mixture of 1-chloro-2-propanol and 2-chloro-1-propanol, which are dehydrochloridated in situ by an equivalent of base (lime))
- Propylene + t-Butyl hydroperoxide → Propylene oxide + t-butyl alcohol
- Propylene + 1-Phenylethylhydroperoxide → Propylene oxide + 1-Phenylethanol (which is next processed to styrene)
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 hydroperoxide instead of ethylbenzene hydroperoxide and recycles the coproduct (alpha-hydroxycumene) 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.[2]
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.[3]
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.[1]
Uses
Between 60 and 70% of all propylene oxide is consumed making polyether polyols for use in making polyurethane plastics. [4] 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.[5]
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.
References
- ^ "Summary of Sumitomo process from Nexant Reports". Retrieved on 2007-09-18.
- ^ Alex Tullo (2004). "Dow, BASF to build Propylene Oxide" 82 (36): 15.
- ^ "Safety data for propylene oxide".
- ^ "Usage of proplyene oxide, from Dow Chemical". Retrieved on 2007-09-10.
- ^ 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. Retrieved on 2007-08-22.
External links
- WebBook page for C3H6O
- Propylene oxide at the United States Environmental Protection Agency
- Propylene oxide - chemical product info: properties, production, applications.
- Propylene oxide at the Technology Transfer Network Air Toxics Web Site
Wikipedia content modification information:
- This page was last modified on 4 September 2008, at 18:20.
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