Question

Alkanes are considered as paraffins.so,they undergo substitution reaction but not addition reactions. Explain with suitable example ?

Answer 1

here is your answer

Alkanes are already bonded strongly, while alkenes and alkynes have weak

π

-bonds. They want to undergo addition reactions to turn

π

-bonds to stronger

σ

's and become more stable.

Explanation:

Alkenes and alkynes are unsaturated - they have

π

-bonds, so don't have the full number of hydrogen that they could have.

This means that they are more unstable than alkanes, since

π

-bonds aren't as strong as

σ

-bonds. The alkenes and alkynes want to form more

σ

-bonds and have a structure more like an alkane, so they undergo addition reactions.

Addition reactions are where more atoms are added to the molecule, not swapped or taken away. This means that the

π

-bonds have to be taken away and used as

σ

-bonds with the new atoms, rather than the

σ

-bonds already there being reattached - it's easier to break

π

than

σ

.Alkanes do not undergo this reaction because they already only have single

σ

-bonds, and so they cannot become more stable or stronger structurally - they are already at the peak, and so can only swap things around in substitution reactions.