acetylene

Acetylene, or ethyne, C2H2, is the simplest alkyne. It is a linear, diatomic carbon with a carbon–carbon triple bond. At room temperature it is a colorless, highly flammable gas that forms explosive mixtures with air under certain conditions.

Industrial production is mainly by the hydrolysis of calcium carbide: CaC2 + H2O → C2H2 + Ca(OH)2. For safe handling, acetylene is stored in cylinders with a porous filler and dissolved in acetone (or dimethylformamide) under pressure, because pure compressed acetylene is unstable.

In chemistry, acetylene undergoes diverse addition reactions across its triple bond, and it serves as a building block for many organic syntheses, including acetylides for coupling reactions. It is also widely used as a fuel gas in welding and metal cutting, due to the high flame temperature of its oxyacetylene flame.

Safety: It is highly flammable and can detonate in the presence of strong shock, heat, or friction when pressurized. Cylinders must be vented, kept away from oxidizers, and used with proper regulators and ventilation. Environmental impact is limited but spills can present hazards.

History: Discovered by Edmund Davy in 1836; industrially important in the 20th century.