Why do unsaturated hydrocarbons show addition reaction?
The catalytic addition of hydrogen to 2-butyne not only serves as an example of such an addition reaction, but also provides heat of reaction data that reflect the relative thermodynamic stabilities of these hydrocarbons,. From the heats of hydrogenation it would appear that alkynes are thermodynamically less stable than alkenes to a greater degree than alkenes are less stable than alkanes.
