Propadiene
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| Names | |||
|---|---|---|---|
| IUPAC name
Allene[1]
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| Preferred IUPAC name
Propa-1,2-diene[2] | |||
| Systematic IUPAC name
Propadiene | |||
| Identifiers | |||
3D model (JSmol)
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| 1730774 | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider | |||
| ECHA InfoCard | Lua error in Module:Wikidata at line 880: attempt to index field 'wikibase' (a nil value). Lua error in Module:Wikidata at line 880: attempt to index field 'wikibase' (a nil value).Lua error in Module:EditAtWikidata at line 29: attempt to index field 'wikibase' (a nil value). | ||
| EC Number |
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| E number | Lua error in Module:Wikidata at line 880: attempt to index field 'wikibase' (a nil value). | ||
| 860 | |||
| MeSH | Propadiene | ||
PubChem CID
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| UNII | |||
| UN number | 2200 | ||
CompTox Dashboard (EPA)
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| Properties | |||
| C3H4 | |||
| Molar mass | 40.065 g·mol−1 | ||
| Appearance | Colorless gas | ||
| Melting point | −136 °C (−213 °F; 137 K) | ||
| Boiling point | −34 °C (−29 °F; 239 K) | ||
| log P | 1.45 | ||
| Hazards | |||
| GHS labelling: | |||
| GHS02: Flammable[3] | |||
| Danger | |||
| H220[3] | |||
| P210, P377, P381, P410+P403[3] | |||
| NFPA 704 (fire diamond) | |||
| Explosive limits | 13% | ||
| Safety data sheet (SDS) | External MSDS | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Propadiene (/proʊpəˈdaɪiːn/) or allene (/ˈæliːn/) is the organic compound with the formula H2C=C=CH2. It is the simplest allene, i.e. a compound with two adjacent carbon double bonds.[4] As a constituent of MAPP gas, it has been used as a fuel for specialized welding.
Production and equilibrium with methylacetylene
[edit | edit source]Propadiene exists in equilibrium with methylacetylene (propyne) and the mixture is sometimes called MAPD for methylacetylene-propadiene:
- H3C−C≡CH ⇌ H2C=C=CH2
for which Keq = 0.22 at 270 °C or 0.1 at 5 °C.
MAPD is produced as a side product, often an undesirable one, of dehydrogenation of propane to produce propene, an important feedstock in the chemical industry. MAPD interferes with the catalytic polymerization of propene.[5]
Occurrence in Space
[edit | edit source]In 2019 it was announced that propadiene had been detected in the atmosphere of Saturn's moon Titan using the NASA Infrared Telescope Facility.[6] This was the first time that propadiene had been detected in space, and the second structural isomeric pair (paired with propyne) detected in Titan's atmosphere, after HCN-HNC.[7][8]
References
[edit | edit source]- ^ https://www.ebi.ac.uk/chebi/CHEBI:37601
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ a b c Record of Allene in the GESTIS Substance Database of the Institute for Occupational Safety and Health, accessed on 17 November 2020.
- ^ IUPAC, Compendium of Chemical Terminology, 5th ed. (the "Gold Book") (2025). Online version: (2006–) "allenes". Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
- ^ Klaus Buckl, Andreas Meiswinkel "Propyne" in Ullmann's Encyclopedia of Industrial Chemistry, 2008, Wiley-VCH, Weinheim. Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
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