Page "Alkyne" Paragraph 13

Alkynes characteristically undergo reactions that show that they are " doubly unsaturated ," meaning that each alkyne unit is capable of adding two equivalents of H < sub > 2 </ sub >, halogens or related HX reagents ( X = halide, pseudohalide, etc .).

Depending on catalysts and conditions, alkynes add one or two equivalents of hydrogen.

Hydrogenation to the alkene is usually more desirable since alkanes are less useful: