Dibromoacetylene is a molecular chemical compound containing acetylene, with its hydrogen substituted by bromine.
Dibromoacetylene can be made by reacting 1,1,2-tribromoethylene with potassium hydroxide. This method has a danger of causing explosions.[1]
Another way is to react acetylene with phenyl lithium (at −50 °C) to make lithium acetylide, which then reacts with bromine to yield the product.[2]
Yet another way is to react acetylene with sodium hypobromite NaOBr.[3]
Dibromoacetylene is explosive and sensitive to air.[3] Its appearance is a clear water like liquid. It has a sweetish smell, but makes a white fume in air that then smells like ozone, possibly because it forms ozone.[1] Dibromoacetylene is lachrymatory.[1]
Dibromoacetylene can be polymerised to polydibromoacetylene using catalysts like titanium tetrachloride and triethylaluminium. Polydibromoacetylene is black, electrically conducting, and stable in air to over 200 °C.[3]
The infrared spectrum has absorption at 2185 cm−1 due to symmetrical stretching on the C≡C bond, 832 cm−1 asymmetrical stretch on C-Br bond, 311 cm−1 bending on Z shape BrCC, 267 symmetrical stretch on all bonds, and 167 cm−1 for C-shaped bending.[1]
In air dibromoacetylene spontaneously inflames producing black sooty smoke and a red flame. When heated, it explodes, yielding carbon and other substances. A slower reaction with oxygen and water, yields oxalic acid and hydrobromic acid and other bromine containing substances. A reaction with hydrogen iodide yields dibromoiodoethylene.Dibromoacetylene reacts with bromine to yield tetrabromoethene.[4]
Dibromoacetylene reacts with Apiezon L, which is used as a vacuum grease in distillation, so its use is unsuitable with this chemical.[1]