Ethylene, C2H4

Ethylene, Ethene, Olefiant gas, or Heavy Carburetted Hydrogen was first obtained by Becher from alcohol by heating it with sulphuric acid. It was mentioned by Priestley in his Experiments and Observations on Air, but first properly studied in 1795 by the four Dutch chemists, Deimann, Paets van Troostwyk, Bondt, and Lauwerenburgh, who observed the oily liquid it produced on combination with chlorine. This liquid, ethylene dichloride, was named Dutch liquid from the nationality of its discoverers, and the gas itself was called olefiant (i.e. oil-forming) gas by Fourcroy.

The difference between ethylene and methane was observed by Henry in 1805, and the denser gas was called heavy carburetted hydrogen to distinguish it from methane, which was light carburetted hydrogen, these two gases being the only hydrocarbons known at that time.

The name ethylene is derived from the name of the alcohol (ethyl) whence it is prepared (cf. propylene from propyl alcohol); and the designation ethene is due to the Geneva Convention (1892), which applied the suffixes -ane, -ene, -ine in accordance with diminishing hydrogen content, thus:

Ethane – C₂H₆;
Ethene – C₂H₄;
Ethine – C₂H₂;

Ethylene is formed as a product of the dry distillation of many organic substances, e.g. salts of aliphatic acids, fats, resins, and coal.