Because the carbonyl carbon is bonded directly to a leaving group, however, the tetrahedral intermediate quickly collapses, expelling the leaving group (X in the figure below) and re-forming the trigo...Because the carbonyl carbon is bonded directly to a leaving group, however, the tetrahedral intermediate quickly collapses, expelling the leaving group (X in the figure below) and re-forming the trigonal planar, sp 2 -hybridized carbonyl. As we shall soon see, these reactions are especially important in the metabolism of lipids (fats and oils) and in the formation and breakdown of peptide bonds in proteins.
