Here is the best flowchart you’ll ever learn in your life. Seriously.
Professors rarely tell you which mechanisms to use. Instead, they’ll give you a set of reagents and ask you to figure it out yourself. This flowchart basically explains that entire process. Let’s go!
When do you use this flowchart? Whenever you have a nucleophile and a GOOD leaving group.
Concept #1: Overview of the flowchart.
In general, the left side of the flowchart predicts SN2 /E2 mechanisms, and the right side predicts SN1/E1 mechanisms, but there are exceptions.
Concept #2: How to predict SN2 and E2 mechanisms.
Here is a list of some more bulky bases that some professors like to use. Be aware that this is not a comprehensive list!
You may also see NaNH2 and NaH (small, non-nucleophilic bases) react via an E2 for primary leaving groups, so keep that in mind!
Concept #3: How to predict SN1 and E1 mechanisms.