| |||
Names | |||
---|---|---|---|
Preferred IUPAC name
Propadiene
[1] | |||
Other names
Allene
[1]
Propadiene | |||
Identifiers | |||
3D model (
JSmol)
|
|||
1730774 | |||
ChEBI | |||
ChEMBL | |||
ChemSpider | |||
ECHA InfoCard | 100.006.670 | ||
EC Number |
| ||
860 | |||
MeSH | Propadiene | ||
PubChem
CID
|
|||
UNII | |||
UN number | 2200 | ||
CompTox Dashboard (
EPA)
|
|||
| |||
| |||
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: | |||
[2] | |||
Danger | |||
H220, H280 [2] | |||
P210, P377, P381, P410+P403 [2] | |||
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).
|
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. [3] As a constituent of MAPP gas, it has been used as a fuel for specialized welding.
Allene 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]
The name allene, for CH2=C=CH2, is retained for general nomenclature only; substitution is allowed, but not by alkyl or any other group that extends the carbon chain, nor characteristic groups expressed by suffixes. The systematic name, propadiene, is the preferred IUPAC name.