Question

what is a substitution reaction? why does alkanes give only substitution reaction?

Answer 1

Because alkanes are saturated solution that's why it undergo substitution reaction but alkene and alkyne undergo substitution and addition reaction because they are unsaturated solution.. 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

Answer 2

Substitution reaction (also known as single displacement reaction or single substitution reaction) is a chemical reaction during which one functional group in a chemical compound is replaced by another functional group. Substitution reactions are of prime importance in organic chemistry.