What occurs during a substitution reaction?

In a substitution reaction, a specific atom or group within a molecule is replaced by a different atom or group. This process often occurs in organic chemistry when a reactant is transformed into a product by exchanging parts. A classic example is the substitution of a halogen atom in an alkane with a hydroxyl group to form an alcohol.

The key feature of a substitution reaction is this replacement nature, with the original atom or group being removed and a new one taking its place, maintaining the overall structure of the molecule. This contrasts with addition reactions, where groups are added to the compound, and in some cases, can involve the loss of water as in condensation reactions. Therefore, understanding the mechanics of substitution reactions is fundamental to grasping how chemical transformations occur in organic compounds.