An elimination reaction (E2) is a type of chemical reaction in which a molecule loses a small molecule, typically a proton or a leaving group, to form a double bond. This results in the formation of a new double bond and the elimination of a substituent from the molecule.
The mechanism of an E2 reaction involves a one-step concerted process in which the leaving group and a proton are eliminated simultaneously, resulting in the formation of a double bond. This mechanism is characterized by a strong base and a good leaving group.
The rate of an E2 reaction is directly proportional to the strength of the base. A stronger base will result in a faster reaction rate, as it is better able to abstract a proton from the substrate molecule.
The main difference between E1 and E2 reactions is the mechanism by which they occur. E1 reactions proceed via a two-step process, with the formation of a carbocation intermediate, while E2 reactions occur via a one-step concerted process. Additionally, E1 reactions can occur with weak bases, while E2 reactions require a strong base.
The selectivity of an E2 reaction can be influenced by several factors, including the strength of the base, the steric hindrance of the substrate, and the stability of the alkene product. A strong base, less steric hindrance, and a more stable alkene product will result in a more selective E2 reaction.