Final answer:
Catalytic hydrogenation of alkenes and alkynes results in the formation of alkanes, with alkenes transitioning directly to alkanes and alkynes first forming alkenes and then alkanes upon additional hydrogenation.
Step-by-step explanation:
The catalytic hydrogenation of alkenes results in the formation of alkanes. When an alkene undergoes hydrogenation, hydrogen atoms are added to each of the carbon atoms involved in the double bond, breaking the double bond and forming a single bond between them. This addition happens in the presence of a catalyst, usually a transition metal such as nickel (Ni), palladium on carbon (Pd/C), or platinum on carbon (Pt/C).
For example, the hydrogenation of trans-3-heptene would result in the formation of 3-heptane. Similarly, hydrogenating 4-methyl-1-hexene would yield 4-methylhexane. The hydrogenation process can also partially reduce alkynes to alkenes or fully to alkanes depending on the reaction conditions and the amount of hydrogen used.
An alkyne like 2-heptyne or 3,4-dimethyl-1-pentyne when subjected to catalytic hydrogenation would initially form an alkene and further hydrogenation would lead to the corresponding alkane.