Alkynes - Ethyne

Ethyne

Ethyne is an unsaturated hydrocarbon with a triple bond.

Preparation of ethyne in the laboratory

Ethyne is prepared by the action of water on calcium carbide.

Preparation of ethyne

The gas thus produced is collected by the downward displacement of water.

Physical properties

It is a colourless gas with garlic-like odour when pure. It is soluble in organic solvents. It is poisonous and highly explosive.

Chemical properties

Combustion

It burns in air with a sooty flame to produce carbon dioxide and water vapour. The flame is white, sooty and produces an extremely high temperature of 4000⁰C.

Addition reactions

Ethyne undergoes addition reactions to give saturated compounds.

a. Chlorination

b. Bromination

Uses

• Illuminant in acetylene lamps.

• Oxy-acetylene torches for welding metals.

• Starting material for the synthesis of organic compounds like acetaldehyde, acetic acid, ethyl alcohol and tetrachloroethane. Tetrachloroethane is a solvent and is also called Westron.