Alküünides

Alküünides are a class of organic compounds characterized by the presence of at least one carbon-carbon triple bond. The general formula for an alküünide with one triple bond is CnH2n-2. The simplest alküünide is ethyne, also known as acetylene, with the formula C2H2. The triple bond consists of one sigma bond and two pi bonds. This makes alküünides highly unsaturated.

Alküünides are typically linear molecules around the triple bond due to the sp hybridization of the carbon atoms involved. This geometry influences their reactivity. The pi bonds in the triple bond are more easily broken than the sigma bond, making alküünides susceptible to addition reactions. Common reactions include hydrogenation, halogenation, and hydrohalogenation, where atoms or groups are added across the triple bond.

The synthesis of alküünides often involves dehydrohalogenation of vicinal or geminal dihalides using a strong base. For example, the reaction of 1,2-dibromoethane with sodium amide produces ethyne. Alküünides have various applications, particularly ethyne, which is used in welding due to the high temperature of its flame when burned with oxygen. They also serve as precursors in the synthesis of polymers, pharmaceuticals, and other organic chemicals. The acidity of terminal alküünides, those with a triple bond at the end of a carbon chain, is noteworthy due to the high s-character of the sp hybridized carbon, allowing them to be deprotonated by strong bases to form acetylides.