Carbonyl compounds can be placed in one of two groups: those that contain a group that can be replaced by another group (Class I), and those that do not contain a group that can be replaced by another group (Class II).
Chapter 11 discusses the reactions of Class I carbonyl compounds. There are a lot of reactions in this chapter, but they all follow essentially the same mechanism. Read Sections 11.5 and 11.7 carefully. They teach you how to readily predict the products of all the reactions in this chapter. Make sure that you see that all Class I carbonyl compounds react with nucleophiles in the same waythey form an unstable tetrahedral intermediate that collapses by eliminating the weakest base.
Carboxylic acids are the most common of the Class I carbonyl compounds both in the laboratory and in biological systems. Because carboxylic acids are not very reactive, they must be activated if they are to undergo reactions at a reasonable rate. This chapter describes the methods chemists use to activate carboxylic acids and compares these methods with the ways carboxylic acids are activated in biological systems.