Question

Name the functional group of organic compounds that can be hydrogenated. With the help of a suitable example, explain the process of hydrogenation, mentioning the conditions of the reaction and any one change in physical property with the formation of the product. Name any one natural source of organic compounds that are hydrogenated.

Answer 1

The functional group of organic compounds that can be hydrogenated are double bonds in alkenes and triple bonds in alkynes.

Hydrogenation is the process of addition of hydrogen to an unsaturated hydrocarbon, in the presence of a catalyst, in order to convert it into a saturated hydrocarbon.
For example, alkene (double bond) can be converted to an alkane (single bond) by adding hydrogen in the presence of a catalyst.

Vegetable oil (unsaturated compound) is heated with hydrogen in the presence of the catalyst nickel to form saturated fat (vegetable ghee).
The chemical equation for the above reaction is as follows:
R₂C=CR₂ + H₂ → R₂CH-CHR₂ (R is the alkyl group)

Vegetable oils, at room temperature, are in the liquid state. On hydrogenation, they convert to a solid or semi-solid state. Their physical properties such as melting point and boiling point changes.

Vegetable oils are the natural organic compounds that can be hydrogenated.