In this chapter, we will extend our discussion, begun in chapter 6, of those organic reactions commonly known as 'nucleophilic substitutions'. In doing do, we will have an opportunity to consider in greater detail the various factors affecting the three main players in most organic reaction mechanisms: the nucleophile, the electrophile, and the leaving group. We will also see, for the first time, how stereochemical concepts are applied to the analysis of an organic reaction.
As we tackle this new and challenging chemistry, it is very important to keep in mind the central ideas that we learned in the acid-base chapter about electron density and how it is stabilized. At that time, we were talking about the breaking and forming of bonds to acidic hydrogens. Now, we will extend our discussion to reactions involving bonds between heteroatoms and carbon - but for much of what concerns us in this chapter, all of the fundamental ideas we’ve learned about electron density still apply!