Alkyl halides substitution versus elimination

Chapters 11 and 12 discuss reactions of alkyl halides to give either substitution or elimination products. It is clear from Chapter 12 that elimination occurs when the nucleophile is also a strong base and when substitution is inhibited due to steric hindrance. There are many cases in which substitution and elimination compete, particularly when the substrate is a secondary alkyl halide. The solvent plays an important role in these reactions, and solvent identification is a key parameter for distinguishing bimolecular versus unimolecu-lar (ionization) processes. The nature of the alkyl halide (1°, 2°, or 3°) is important, as is the strength of the nucleophile and whether or not that nucleophile can also react a strong base. This chapter will discuss those factors that influence both substitution and elimination, as well as introduce several assumptions that will help make predictions as to the major product. 

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