Alpha Substitution enolate ion Copyright 2010 Pearson Prentice Hall,Inc. Alpha substitution is the substitution of one of the hydrogens attached to the alpha-carbon for an electrophile. The reaction occurs through an enolate ion intermediate. Chapter 22 2 Chapter 22 2 Alpha Substitution ▪ Alpha substitution is the substitution of one of the hydrogens attached to the alpha-carbon for an electrophile. ▪ The reaction occurs through an enolate ion intermediate