91Ó°ÊÓ

Oxidation refers to the process when an increase in the number of C-Z bonds or a decrease in the number of C-H bonds takes place. Z refers to elements that are more electronegative than the carbon atom; for example, oxygen, nitrogen, and halogens.

Reduction is a process when a decrease in the number of C-Z bonds and an increase in the number of C-H bonds takes place.

The replacement of C-H bonds with C-Z decreases the electron density around the carbon atom, thereby resulting in oxidation.

a. In the following reaction, the formation of a new C-O bond has occurred. Since oxygen is more electronegative than carbon, it causes a decrease in the electron density around carbon. Hence, oxidation takes place in the following reaction:

Oxidation takes place

Reduction takes place

The carbon atom in the above reaction has formed two new C-H bonds after removing a double bond with an oxygen atom.

c. In this reaction, there is no overall change in the number of C-H and C-O bonds. Therefore, there is neither oxidation nor reduction taking place in the given reaction.

Neither oxidation nor reduction takes place

d. There is a decrease in the number of C-O bonds, and an increase in the number of C-H bonds. Therefore, reduction takes place in the following reaction:

Reduction takes place