Formation and Stability of Enolate lons O H :0 R 1R'+OR R-C- R- ROH pKa=16-18 ketone or aldehyde major pKa20 enolate ion Example :Q一CH,CH3 CHCH,OH pKa=15.9 cyclohexanone ethoxide ion cyclohexanone enolate pKa =19 (equilibrium lies to the left) Copyright2010 Pearson Prentice Hall,Inc. The equilibrium mixture contains only a small fraction of the deprotonated,enolate form. Chapter 22 10 Chapter 22 10 Formation and Stability of Enolate Ions ▪ The equilibrium mixture contains only a small fraction of the deprotonated, enolate form