Question

What name is given to a class of reactions that transforms saturated hydrocarbons into unsaturated hydrocarbons?

Answer 1

The name given to the class of the reaction that transforms saturated hydrocarbon (or Alkanes) into unsaturated hydrocarbons (Alkenes or Alkynes) is Cracking (or Pyrolysis). 

The Pyrolysis Reaction usually occurs at the high temperature and mostly under the Presence of Aluminium oxide. 

The Reaction for the Cracking of the Alkanes are ⇒

1) C₂H₆ -----Heat (Δ)-----→ C₂H₄ +H₂

In this Reaction, Alkanes (Ethane or the Saturated Hydrocarbon) is converted into the Alkenes (Ethene or the Unsaturated Hydrocarbon) by decomposition of the Ethane.


Hope it helps.

Answer 2

Dehydrogenation is a reaction class which transforms the ‘saturated hydrocarbons’ into ‘unsaturated hydrocarbons’.

Explanation:

• Saturated hydrocarbons have only single bonds are present in between the ‘carbon atoms’ in a molecule.

        Example: alkanes – Butane, propane.

• Unsaturated hydrocarbons have either double bond or triple bonds are present in between the carbon atoms in a molecule.

         Example: Alkenes (Double bond is present in between

         carbon atoms)- Ethene, propene.

         Alkynes (Triple bond is present in between carbon atoms)

         – Ethyne,  propyne.

• A ‘chemical reaction’ which involves a removal of hydrogen atoms are called dehydrogenation.

          $H_{3} C-C H_{3} \quad \stackrel{\text { Dehydrogenation }}{\longrightarrow} H_{2} C=C H_{2}$

• The dehydrogenation of alkanes (saturated compound) gives alkene (unsaturated compound).