By now you should know a decent amount of different reactions. This section is dealing with a very specific group of reactions that you should know very well- substitution and elimination reactions. Odds are, you already know a reaction that falls into one of these categories without even knowing it. You’ll need to know what each mechanism does, and more importantly, how the mechanism proceeds. You’ll also need to recognize the conditions that would lead to either type of reaction to occur.
The obvious difference between substitution and elimination reactions is that substitution reactions replace one substituent with another while elimination reactions simply remove the substituent. However, there are more specific differences you will need to be familiar with.
Within the category of substitution and elimination reactions, there are more subcategories. Specifically, SN1, SN2, E1, and E2 (Substitutions 1 and 2, Eliminations 1 and 2). The major difference between the groups is the number of steps the reaction takes place over. Make sure you are comfortable with the differences between the groups and know what conditions are required for a given reaction to take place- this will likely be crucial information on exams.
