James Richard Fromm
Alkynes are hydrocarbons which contain a triple carbon-carbon bond. As with alkenes, the simplest member of the series is the two-carbon molecule. The triple bond is indicated by changing the ending of the name to -yne, in the same manner as the double bonds in alkenes are indicated by the ending -ene. Alkynes, like alkenes are unsaturated hydrocarbons with the general formula CnH2n-2. They are very unstable and quite reactive. For example, ethyne the simplest alkyne,
Structure of Ethyne, Acetylene
which is more commonly known by its common name acetylene, is a gas often used as a fuel for cutting and welding torches because it burns with a very hot flame.
The alkynes follow much the same pattern of reactivity and nomenclature as do the alkenes. However, the alkynes which have the triple bond at the end of the molecule often have the terminal hydrogen relatively acidic, while no other hydrogen on the alkyne or on the corresponding alkene is even slightly acidic. This acidity arises because the bonding electrons of the terminal hydrogen tend to associate themselves with the electrons in the triple bond, lending a considerable ionic character to the bond to hydrogen.
| Alkynes | |
|---|---|
| Ethyne | C2H2 |
| Propyne | C3H4 |
| Butyne | C4H6 |
| Pentyne | C5H8 |
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| Propyne |
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