Question

Explain why alkynes are less reactive than alkenes toward addition of $Br_{2}$.

Answer 1

Hydrocarbons are compounds which are mixture of "carbon" and "hydrogen". Depending on the bonding in between the carbon and hydrogen atoms, it can be classified as "alkanes", "alkenes", and "alkynes".

Due to its "higher electron density", the triple bonds present in the alkynes are easily attacked by "electrophiles", but are "less reactive" than "alkenes" due to the "compact" “C-C electron bond. As the “electrophilic addition” of non-symmetric alkenes follows the Markovnikov rule, adding the electrophilic to the “less substituted” carbon.