Propadiene

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.

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.

[4] 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.

Stereo structural formula of propadiene with explicit hydrogens
Stereo structural formula of propadiene with explicit hydrogens
Spacefill model of propadiene
Spacefill model of propadiene
Ball and stick model of propadiene
Ball and stick model of propadiene
NFPA 704 four-colored diamond Health 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g. sodium chloride Flammability 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propane Instability 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxide Special hazards (white): no code