How to Determine ALL Products From an E1 Reaction

The Key Is The The Carbocation

I had a student ask if I could make up an E1 question that incorporates many different products. Well, here it is…

Since we know this is an E1 mechanism, we first need to generate a carbocation:



Look for alpha hydrogens

Next, we need to look for hydrogens that are alpha to the carbocation (hydrogens on the adjacent carbon(s):



There is only one site with hydrogens; the other is a quaternary center.



As you have guessed, this can’t be the only final product and the whole story…there must be something else we can do. Let’s take a look at the quaternary center again:



We can see the driving force for this migration. We can go from a secondary carbocation to a teriary carbocation, which is more stable. Now, let’s see how many products we can form:



With this alkyl migration, we were able to squeak out 3 more products (a total of 4 products). See if you can rank them from highest to lowest priority.

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