Propadiene
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Names | |||
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IUPAC name
Allene | |||
Systematic IUPAC name
Propa-1,2-diene (substitutive) Dimethylenecarbon, dimethylenemethane (additive) | |||
Identifiers | |||
1730774 | |||
463-49-0 | |||
ChEBI | CHEBI:37601 | ||
ChEMBL | ChEMBL116960 | ||
ChemSpider | 9642 | ||
EC number | 207-335-3 | ||
860 | |||
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Jmol-3D images | Image Image | ||
MeSH | Propadiene | ||
PubChem | 10037 | ||
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UN number | 2200 | ||
Properties | |||
Molecular formula |
C3H4 | ||
Molar mass | 40.06 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 | |||
MSDS | External MSDS | ||
EU classification | F+ | ||
R-phrases | R12 | ||
S-phrases | S9, S16, S33 | ||
NFPA 704 | |||
Explosive limits | 13% | ||
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa) | |||
verify (what is: / ?) | |||
Infobox references | |||
Propadiene is the organic compound with the formula H2C=C=CH2. It is the simplest allene, a compound with conjoined C=C double bonds.[1] As a constituent of MAPP gas, it has been used as a fuel for specialized welding.
Production and equilibrium with methylacetylene
Allene exists in equilibrium with methylacetylene, the mixture sometimes being called MAPD for methylacetylene-propadiene:
- H3CC≡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 cracking propane to produce propene, an important feedstock in the chemical industry. MAPD interferes with the catalytic polymerization of propene.[2]
References
- ↑ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "allenes".
- ↑ Klaus Buckl, Andreas Meiswinkel "Propyne" in Ullmann's Encyclopedia of Industrial Chemistry 2008, Wiley-VCH, Weinheim. doi:10.1002/14356007.m22_m01
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