Propadiene
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| Template:Longitem | Template:Unbulleted list |
| Template:Longitem | 1730774 |
| ChEBI | Template:Unbulleted list |
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| EC Number | Template:Unbulleted list |
| Template:Longitem | 860 |
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| MeSH | Propadiene |
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| RTECS number | Template:Unbulleted list |
| UN number | 2200 |
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| Template:Longitem | Template:Chembox Elements/molecular formula |
| Molar mass | Template:Chem molar mass |
| Appearance | Colorless gas |
| Melting point | Template:Chembox CalcTemperatures |
| Boiling point | Template:Chembox CalcTemperatures |
| log P | 1.45 |
| NFPA 704 (fire diamond) | Template:NFPA 704 diamond |
| Explosive limits | 13% |
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Propadiene (Template:IPAc-en) or allene (Template:IPAc-en) is the organic compound with the formula Template:Chem2. It is the simplest allene, i.e. a compound with two adjacent carbon double bonds.[3] As a constituent of MAPP gas, it has been used as a fuel for specialized welding.
Production and equilibrium with methylacetylene
Propadiene exists in equilibrium with methylacetylene (propyne) and the mixture is sometimes called MAPD for methylacetylene-propadiene:
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.[4]
Occurrence in Space
In 2019 it was announced that propadiene had been detected in the atmosphere of Saturn's moon Titan using the NASA Infrared Telescope Facility.[5] 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.[6][7]
References
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- ↑ a b c Record of Allene in the GESTIS Substance Database of the Institute for Occupational Safety and Health, accessed on 17 November 2020.Script error: No such module "TemplatePar". Script error: No such module "TemplatePar". Script error: No such module "TemplatePar".
- ↑ IUPAC, Compendium of Chemical Terminology, 5th ed. (the "Gold Book") (2025). Online version: (2006–) "allenes". Script error: No such module "CS1 identifiers".Script error: No such module "TemplatePar".
- ↑ Klaus Buckl, Andreas Meiswinkel "Propyne" in Ullmann's Encyclopedia of Industrial Chemistry, 2008, Wiley-VCH, Weinheim. Script error: No such module "CS1 identifiers".
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