FIGURE 19.1
A nucleophilic addition reaction to a ketone or aldehyde. The attacking nucleophile apperoaches the carbonyl group from a direction approximately 45o to the plane of the sp2orbitals,the carbonyl carbon rehybridizes from sp2 to sp3 and alkoxide ion is formed. In an example of the reaction, electrostatic potential maps of acetone, cyanide ion nucleophile, and the alkoxide ion addition product show how electron density is transferred from the nucleophile to the oxygen atom.