Vinylacetylene

It is composed of both alkyne and alkene groups and is the simplest enyne.

Vinylacetylene is extremely dangerous because in high enough concentrations (typically > 30 mole percent, but pressure dependent) it can auto-detonate (explode without air being present) especially at elevated pressures, such as those seen in chemical plants processing C4 hydrocarbons.

[2] An example of such an explosion occurred at a Union Carbide plant in Texas City in 1969.

[citation needed] At one time, chloroprene (2-chloro-1,3-butadiene), an industrially important monomer, was produced via the intermediacy of vinyl acetylene.

This allene derivative which, in the presence of cuprous chloride, rearranges to 2-chloro-1,3-butadiene:[8]

NFPA 704 four-colored diamond Health 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroform 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 hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid