Answer Problem 39, parts a–h, using 2-butyne as the starting material instead of propyne.
g. excess H₂, Pd/C

Hydrogenation of alkynes involves the addition of hydrogen (H2) across the triple bond, converting it into an alkene or alkane. In the presence of a catalyst like palladium on carbon (Pd/C), this reaction can proceed efficiently. For 2-butyne, excess H2 will fully saturate the triple bond, resulting in the formation of butane.

Catalytic hydrogenation is a process where hydrogen gas is added to unsaturated organic compounds in the presence of a catalyst. The catalyst lowers the activation energy required for the reaction, allowing for faster conversion. In this case, Pd/C serves as an effective catalyst for the hydrogenation of 2-butyne to butane.

Understanding the reaction mechanism is crucial for predicting the outcome of chemical reactions. In the case of hydrogenation, the mechanism involves the adsorption of the alkyne onto the catalyst surface, followed by the addition of hydrogen atoms to the carbon atoms of the triple bond. This stepwise process leads to the formation of the saturated product, butane, from 2-butyne.