Carbenes – Formation (via alpha elimination)

NOTE: Important charges and non-bonding electrons are shown throughout the animation except during the transition phase

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α elimination (eliminations in which both the proton and the leaving group are located on the same atom) follow a mechanism akin to an E1cB β-elimination. A strong base removes an acidic proton adjacent to an electron withdrawing group to give a carbanion. Loss of a leaving group from the carbanion creates a carbene. One of the best known elimination reactions occurs when chloroform is treated with base, forming a dichlorocarbene.

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P. de Frémont, N. Marion and S. P. Nolan, Coord. Chem. Rev., 2009, 253, 862–892.