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Names | |
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Preferred IUPAC name
1,2-Dibromoethyne
[1] | |
Identifiers | |
3D model (
JSmol)
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ChemSpider | |
PubChem
CID
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CompTox Dashboard (
EPA)
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Properties | |
C2Br2 | |
Molar mass | 183.830 g·mol−1 |
Melting point | −16.5 °C (2.3 °F; 256.6 K) |
Except where otherwise noted, data are given for materials in their
standard state (at 25 °C [77 °F], 100 kPa).
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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. [2]
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. [3]
Yet another way is to react acetylene with sodium hypobromite NaOBr. [4]
Dibromoacetylene is explosive and sensitive to air. [4] 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.[ how?] [2] Dibromoacetylene is lachrymatory. [2]
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. [4]
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. [2]
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. [5]
Dibromoacetylene reacts with Apiezon L, which is used as a vacuum grease in distillation, so its use is unsuitable with this chemical. [2]