When an elimination reaction occurs, a molecule typically loses elements from its structure, often resulting in the formation of a double or triple bond. This process leads to a decrease in the number of hydrogen atoms or other substituents attached to the carbon atoms, thereby increasing the degree of unsaturation.
For instance, in a typical dehydrohalogenation reaction, a halide (like Cl or Br) and a hydrogen atom are removed from adjacent carbon atoms in an alkyl halide. The removal of these two substituents allows the remaining carbon atoms to form a double bond, transforming the saturated structure into an unsaturated one. This change is significant because it alters the molecule’s chemical properties, making it more reactive and allowing it to participate in various addition reactions.
Ultimately, the concept of unsaturation refers to the presence of multiple bonds in a molecule, and elimination reactions are a key way by which molecules can achieve greater unsaturation.