On roadmap #2, last row from the bottom, all the way to the left: Is this E1 or E2 and why?
On roadmap #3, just to the right of "start": Can someone explain the difference in the equations directly upwards and downwards?
Any help would be greatly appreciated 🙂
ANY, ANY, ANY time you have a strong base such as ethoxide, it will go either E2 or Sn2. When you see that strong base, KNOW IMMEDIATELY that it will be either E2 or Sn2. What gets tricky is deciding which one of those 2 it will go.
For the second question. In this case, both ways go E2. Going up, you are using a tert butoxide. What do you recognize this as? ANY, ANY, ANY time you see tert butoxide, you will always get E2! Recognize this immediately. The ONLY exception is a methyl with a leaving group, however, this should be obvious that it cannot go E2, there is only 1 carbon.
As mentioned above, t-butoxide is a strong base. However, it is also very "bulky." That is, its very sterically hindered. Draw out the full structure to see what I mean. So when you see a strong, bulky base (tert butoxide is very common), recognize E2.
Now that you know it is E2, it is a rule that with a BULKY base, you will get the LEAST substituted product. This is known as the Hoffman rule. There are reasons for this, but I'm short on time.
For the one going down, again it is E2. Recognize that your only choices, because it is a strong base are E2 and Sn2. Why? Because it is a strong base. In this case it goes E2 because the carbon that is attached to the leaving group is very hindered. In fact, it is tertiary, VERY hindered.
However, in this case, because the strong base is NOT HINDERED, it will form the least substituted carbon. This is known as the Saytzev rule. (google these terms for more info).
E2/SN2/E1/SN1 is very tricky, IMO. I would highly, highly recommend getting a textbook and reading about it in depth. Or talk to an ochem instructor or something.
There are many questions that I can draw out and debate with myself whether it will go Sn2 or E2, etc, that Destroyer never addresses. So any more framework you can get in these topics will only help.
Good luck.
