Substitution and Elimination Reactions

Return to Organic Chemistry 1 Syllabus

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.

What to know about substitution and elimination reactions

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.

5 Curated Resources

Here’s the link to Khan Academy’s overview of substitution and elimination reactions, which is always a good place to start learning new material.

Choosing Reactions

free, Video

This is a pretty quick video that touches on conditions needed for SN and E reactions. The videos on this channel are usually quick and to the point, so it’s probably worth exploring for other topics, especially regarding reactions.

This is a decent way to learn what conditions are required for a substitution or an elimination reaction to proceed.

Deciding SN1/SN2/E1/E2

free, Article

Here’s another good resource for learning when to pick what reaction.

As per usual, the best way to learn this is to practice. Here are some good practice problems to learn substitution and elimination.