Question

What is the reactive site for addition reactions in unsaturated hydrocarbons? Give one example?

Answer 1

The organic compounds containing carbon atoms ($\mathrm{C}$) having multiple bonds either double bond or triple bonds between two carbon atoms are called unsaturated hydrocarbons.

Alkenes and alkynes are unsaturated hydrocarbons that contain double bonds$\mathrm{C}=\mathrm{C}$ and triple bonds $\mathrm{C}\equiv \mathrm{C}$ between the carbon atoms.

In unsaturated hydrocarbons, olefinic carbons are present.

The double bonds and triple bonds acts as reactive sites for addition reactions in unsaturated hydrocarbons.

Example: The addition reaction of Bromine molecule to an alkene is written as:

${\mathrm{CH}}_2={\mathrm{CH}}_2+{\mathrm{Br}}_2\stackrel{{\mathrm{CCl}}_4}{\to }{\mathrm{BrCH}}_2-{\mathrm{CH}}_2\mathrm{Br}$

The Bromine molecule attacks the olefinic carbon to give the 1,2-dibromoethane (${\mathrm{BrCH}}_2-{\mathrm{CH}}_2\mathrm{Br}$) as the major product.