Chemical Properties of Ethyne
Ethyne (acetylene) Colourless, flammable gas (C2H2), manufactured by cracking of petroleum fractions. The simplest alkyne, it is explosive if mixed with air. When burned with oxygen, it produces extremely high temperatures up to 3480°C (6300°F) and is used in oxyacetylene torches. It is polymerized to manufacture plastics, synthetic fibres, resins and neoprene. It is used to produce ethanal and ethanoic acid. Properties: r.d. 0.625; m.p. ?80.8°C (?113.4°F); b.p. ?84°C (?119.2°F).
Ethyne burns in air with sooty flame and gives carbon dioxide, water and heat.
Addition of hydrogen
Ethyne on addition with hydrogen forms intially ethene and finally forms ethane.
Reaction with halogens
Ethyne reacts with halogen acids to form 1,2-Tetra halo ethanes.
Oxidation of ethyne
Ethyne undergoes oxidation or combustion reactions. Ethyne is oxidized to form Oxalic acid in pressence of dilute.KMnO4.
Ethyne reacts with ozone to produce acetylene ozonoide which further hydrolysed in pressence of Zinc to form Glyoxal.
Reaction with HCl
Ethyne on reaction with hydrochloric acid to form 1,1-dichloro ethane.
- Ethyne is useful for artificial ripening and preservation of fruits.
- It is useful in acetylene lamps to generate light.
- Ethyne is used to prepare various organic compounds.
- It is also useful to manufacture important organic compounds like acetic acid, acetaldehyde, ethyl alcohol and polymers like PVC…etc.
- It is useful to produce an oxyacetylene flame.
Chemical tests inorder to distinguish between alkanes, alkenes and alkynes
|Addition of few drops of bromine solution to hydrocarbon||No change observed||Decolurisation of bromine solution||Decolurisation of bromine solution|
|Adding few drops of alkaline. KMnO4||No change observed||Fade in the purple colour observed.||Fade in the purple colour observed.|
|Adding few drops of ammonical silver nitrate||No change||No change||White Precipitate of silver acetylide is formed.|
|Adding few drops of ammonical cuprous chloride||Nochange observed||No change is observed||Red precipitate of copper acetylide is formed.|