ABSTRACT
Haloalkanes can be prepared through radical substitution, addition to alkenes, and addition to alkanes. Because of the greater electronegativity of halogen atoms, the carbon atoms with attached halogen atoms are rendered electrophilic. This chapter explores the chemistry of haloalkanes: substitution and elimination. In a substitution reaction, the halogen atom is replaced by an incoming nucleophile. This can happen in a concerted bimolecular process (SN2) or in a two-step, unimolecular process (SN1). In an SN2, steric hindrance at the electrophilic carbon is a key concern and the basicity of the incoming nucleophile. For an SN1 reaction, the solvent and the stability of the carbocation intermediate play a central role. These two substitution reactions are not binary, but exist along a continuum depending on the conditions present. In addition, elimination, the formation of alkenes, is also possible, depending on nucleophile basicity (SN2) and whether heat is used (SN1). The core of this chapter is understanding what factors influence a reaction one way or another and how to predict the major reaction outcome.
