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Draw a mechanism of formation for the three products from the previous problem on a separate piece of paper.
Draw a mechanism on a separate piece of paper.
Friedel-Crafts reactions have limitations.
You should read about them in your textbook.
We need to understand why an acyl group makes the ring less reactive.
During the upcoming sections, we will explain this in greater detail.
We have one more person to discuss.
We will use the reaction in synthesis problems later in the chapter.
The upcoming sections will explain why this reaction is so important.
Let's just master the reaction and take my word for it.
The electrolyte is SO.
There are three double bonds here.
Double bonds are not such great bonds.
The overlap is not so efficient and it is misleading to think of it as a double bond.
We are going to see a reaction that uses SO.
Any bottle of sulfuric acid will have some SO in it.
From now on, whenever you see SO, you should know that it's the reagent.
This process installs an SO H group on the ring.
Let's take a closer look at the mechanism.
H+ comes off when E+ goes on the ring.
We are not using a net positive charge in this case.
There is no net charge in this case.
We put something on the ring and then took something off of it.
Our ring never gained or lost any charges.
In this case, we are putting something neutral on the ring and then removing something that is positive.
Our mechanism will have an additional step.
The oxygen atom is negatively charged in the presence of sulfuric acid.
The extra step at the end of the mechanism is just a protons transfer.
The core reaction is the same as it has been in all of the previous reactions, with H+ coming off of the ring.
The feature that will make this reaction so important for synthesis problems is how easily the reaction can be reversed.
The amount of product is controlled and sensitive to the conditions.
The equilibrium leans the other way if you use dilute sulfuric acid.
This allows us to remove the SO H group whenever we want.
We can install the SO H group on the ring whenever we want, and we can also remove it whenever we want.
You might wonder why you would want to install a group in the first place.
It would seem like a waste of time.
This will become very important in synthesis problems in the upcoming sections.
Let's make sure we are comfortable with the reagents.
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