Definition

An elimination reaction in which a proton from the beta (b) position is removed together with the leaving group, forming a double bond.

Explanation

Let’s use cyclobromine as an example. In the reaction below, you see bromine attached to the alpha carbon position ( α ), while the hydrogen is attached to the beta position ( β ). In this reaction, the hydrogen is removed by NaOH, kicking bromine off and forming a cycloalkene.

Structural reaction scheme for 1,2-Elimination
Figure. 1,2-Elimination

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