Elimination
Definition and meaning of Elimination in chemistry.
Elimination is a highly prominent type of organic reaction where two substituents are formally removed from a single molecule in either a one- or two-step kinetic mechanism, typically resulting in a new double or triple bond.
In more detail
It remains the principal chemical pathway for synthetically generating reactive alkenes and alkynes in the modern laboratory. Elimination reactions almost always directly compete with nucleophilic substitution reactions, with the dominant pathway largely depending on specific reaction conditions, such as the ambient temperature, solvent polarity, and the exact physical strength of the chemical base used. The two most common foundational pathways are the E1 and E2 mechanisms. In a classic E2 reaction, a strong bulky base aggressively abstracts a susceptible proton while a designated leaving group departs entirely simultaneously, smoothly forming a new pi bond in a single concerted step.
Key facts
| Field | Organic Chemistry |
|---|---|
| Primary Product | Alkenes and alkynes |
| Common Pathways | E1 and E2 mechanisms |
| Competing Reaction | Nucleophilic substitution |
The highly acidic dehydration of liquid ethanol at high temperatures to successfully form gaseous ethene and H2O is a classic, well-documented elimination reaction rapidly catalyzed by a strong acid.
Frequently asked questions
What exact reaction conditions chemically favor an elimination reaction over a substitution reaction?
Applying significantly higher temperatures and utilizing strong, sterically bulky chemical bases generally strongly favor elimination pathways over competing substitution reactions.