Predict the major products formed when benzene reacts (just on...

Question

Predict the major products formed when benzene reacts (just once) with the following reagents.

e. isobutylene + HF

Accepted Answer

Hey everyone And welcome back in today's video. We are going to solve another problem which says identify the major product formed in the reaction between Halloween and propane in the presence of Hydrofluoric asset. So as the problem suggests, we are starting with Halloween. We are going to draw a benzene ring with a metal group that's Halloween. And according to the context of the problem, we are treating it protein remember chain with a double bond in the presence of Hydrofluoric acid. So let's think how this reaction can proceed. Now, what is the role of Hydrofluoric acid here? It can actually generate an electro file. And as the reaction suggests, generally, we're thinking about electrolytic aromatic substitution where we need to produce that electro file. So let's see how that happens if we troll protein. It would essentially react with hydrochloric acid and we would have a protein nation stop where we form our carbon Caroline intermediate recall. That according to the more cognitive school, we are going to add hydrogen to a less substituted position to form a more stable secondary carbo Karen. So instead of adding a positive charge here, we're going to edit at a more stable position. So that's our secondary carbo Karen. So we have generated our electro file and then we are going to think about the electra filic aromatic substitution stuff. We clearly now understand that Hydrofluoric acid was used in the generation of an electro file. And now that we have our electro file. We are ready to proceed with the general mechanism we can draw to win once again and the word first step in this reaction is the attack by the pi bond on our electro file. So let's throw it once again, that will be our electro file. We are adding it to the structure because we are interested in the major product. Keep in mind that even though our metal group is Ortho and para director, the major product will be obtained at the power position to the steroid hinderance effect. Even though it's not so significant, there's just a small method group but it plays a major role in this electrical dramatic substitution. So the major product would be formed here and that's why we're using this. I bond instead of that one. Okay, now we are ready to draw our intermediate and we can say that during the stop we are getting our carbo Karen intermediate. So there's still these two double bonds here we are adding and isopropyl group and we have a positive charge to this position. Now, of course we can draw our residence forms this cardboard Carolina's resonance stabilized. Right? We can say that it can be stabilized. Let's suppose that first of all, we shift these electrons onto disposition to form a carpool khurana at a tertiary position. So that would be our next resonance structure and then we may get another one. What if we simply shift these pi electrons over here to form another secondary carbo cast iron. So our next president structure would look like this. And now this is the step where we can simply show the deep rotation. Stop. Keep in mind that there is one Haijun over here and we can remove it. The way to remove it is to use the fluoride. And I informed in the first step of the generation of an electro file. So the fluoride and iron would simply attack that hydrogen. The bonding electrons would be transferred into the formation of the pi bond. And this is how we get rid of the positive charge and form our final product. So now we are ready to draw the resulting product. Okay so we basically got our product and we may simply draw it as our final answer in the general reaction scheme. So if we go back to our original reaction, we can say that the product of this reaction is the given product. Let's label this is our final answer. And let's review the steps required for this reaction to take place. So we're starting with Halloween and we are going to treat it with propane and the presence of Hydrofluoric acid. We first all understood that Hydrofluoric acid promotes the generation of an electoral file because the double bond can be easily protein ated due to the presence of acidic hydrogen over here using the more cognitive stroll. We understand that we are interested in a more stable secondary carbo Karen. So we have formed that in this step we have formed our electro file that can now participate in the electra Philip aromatic substitution mechanism. We said that the major product will be formed that the power position instead of Ortho due to that minor stereo hindrance effect. So we use one of our pi bonds to add our electro file. Having formed the carbon Karen, we showed several resonance forms and then we said that we are going to D protein ate the carbo Karen to form our final product using the fluoride. And on that was formed in our first step. Right? So we removed that proton, neutralize the carbo. Karen restored our aromatic ring. And we are done. We got our final product. We may simply conclude that the correct answer choice. This multiple choice question is however, if you have any questions, don't have States, leave a comment down below in the comment section and thank you for watching.

Predict the major products formed when benzene reacts (just once) with the following reagents.
e. isobutylene + HF

Key Concepts

Electrophilic Aromatic Substitution

Carbocation Stability

Markovnikov's Rule

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