CHEM 2262 Chapter : Chapter 18
Document Summary
Topics covered and suggested reading for the chapter 18 notes. Nucleophilic intermediates from carbonyl compounds enols and enolates 18. 2. We call such a carbon an -carbon, and we call its attached hydrogens -hydrogens. The anion formed upon deprotonation is stabilized by resonance delocalization of the negative charge. This is illustrated on the right-hand side of the figure below for a carbonyl (c=o) electron-withdrawing group. We call the anion formed by removal of a proton adjacent to a carbonyl group an enolate. The reactions of enolates will be one of the major topics of this chapter. Listed below are some characteristic pka values of -hydrogens activated by adjacent electron- withdrawing groups. Note that attachment of a second electron-withdrawing group to an -carbon further increases the acidity (lowers the pka) of attached -hydrogens. We characterize -carbons as singly activated (1st column) or doubly activated (2nd column) according to the number of electron- withdrawing groups attached to the -carbon.
