| has gloss | eng: The E1cB elimination reaction is a special type of elimination reaction in organic chemistry. This reaction mechanism explains the formation of alkenes from (mostly) alkyl halides through a carbanion intermediate given specified reaction conditions and specified substrates. The abbreviation stands for Elimination conjugate Base. The reaction takes place around a sp3 - sp3 carbon to carbon covalent bond with an α-acidic hydrogen atom substituent and a β-leaving group. This leaving group can be a halide or a sulfonic acid ester such as a tosyl group. A strong base abstracts the α proton generating a carbanion. The electron pair then expels the leaving group and the double bond is formed. When the first step to the carbanion is slow and the second step fast the reaction is irreversible and named (E1cB)i. When the first step is fast and the deprotonation reversible then the reaction mechanism is (E1cB)r. In the (E1cB)anion variation the carbanion is especially stable with a rapid first step and a slow second step. |
