Advantages of Friedel-Crafts Acylation

Now let's discuss how Friedel Crafts Ace Elation is so much more effective than Friedel crafts calculation. So Friedel crafts isolation has several advantages that are going to make it much more synthetically useful than calculation. And a few of these we've already discussed. Basically, the isolation reactions are going to deactivate the ring to further reactions favoring mono substitution, which is a big deal in organic chemistry synthesis. We wanna make sure that we're only adding one group of time at a time. Not too. Not for okay. Also, we learned that isolation reactions are not susceptible to Carvel catting rearrangements because the asili, um, I on can't resonate. Right? Perfect. So here. I just want to show you guys an example of how to sin Theses could go completely different directions, depending on which one you use. Okay, so let's say that we're trying to add a three carbon chain to the benzene, right? Okay. First, I'm gonna use a Soleil shin in isolation. What I'm gonna wind up getting is an a C Liam ion that looks like this. It's gonna be carbon with a dull bon o positive and a three carbon chain. Everyone called that so I'm gonna wind up attacking. And after all of our uranium ions, don't worry about it too much. We're gonna wind up getting a product that looks like this. It's gonna have ah, three carbon chain. It's gonna be a key tone with the three carbon chain and that's it. We're not going to get a second reaction. We're not gonna get a rearrangement. That's it. Cool. Now notice what happens when you try to use calculation. Calculation might seem like the more the better choice because we don't want the key tone. We just want the chain. So our first thought would be Let's just use calculation because calculation doesn't give us that key tone. But guys, alc elation is going to give us so many more problems because look at this. What happens when that bond gives its electrons to the aluminum? Remember, guys, that primary carbon patterns are unstable, right? So that means that a rearrangement is actually gonna happen right in the mechanism right away. This h is gonna wind up doing a 12 hydride shift and making a carbon capture. And it looks like this. So all of a sudden, my carb Acadian doesn't look like a three carbon chain. That's a straight chain. It looks like a branch chain. It's attaching in the middle. So what I'm gonna wind up getting isn't gonna wind up getting now an isopropyl benzene. But that's not all I'm gonna get. I might actually get another isopropyl, or I might even get another one. Who knows? I'm gonna get a poly substituted. Polly isopropyl benzene. All I wanted was a three carbon chain. And look what a disaster this is. This is why calculation is so limited and why we're usually going to go with an isolation over a calculation, because calculation just gives us a mess of rearrange products and possible Polly substituted products. Okay, Now, there is one way to overcome this, which would be, you know, for for this specific reaction, what we could do is we could increase the equivalent of benzene. Okay, now notice here. I put one equivalent each of both of these. If I really want to use calculation, I could increase the equivalent. Let's say I made it to 100 equivalence of benzene. Okay, now, that would promote model substitution. Okay, That would promote model substitution because Now I have excess benzene that most likely isn't gonna find that many carbo candidates to react with. Most likely only Rex with one. But still, that would still give me an isopropyl benzene. So even in that case, I would still have isopropyl benzene causes gonna rearrange. So it's like a solution gives us exactly what we want. But unfortunately, there's that stupid key tone. If Onley there was a way to get rid of that key tone, then we would have a three carbon chain exactly where you want it. Wait, We do have a way to get rid of that Kitson. And that is the glorious advantage of Clements introduction. So it turns out that ace Elation products can be converted toe alcohol, Benzene using a region called a sink amalgam in a reaction called the Clemmensen reduction. Okay, now, the mechanism for this reaction is still unknown. To this day. No one really knows what the mechanism is. Okay, But you do need to recognize and memorize the re agents. Three agents are a zinc mercury amalgam over a strong acid hcl. And what that's gonna give us is it's actually gonna add hydrogen is to where the Carbonell was. And it's just going to give us an alcohol product. Okay? Meaning that guys, if we want to get a three carbon chain instead of using a calculation, I could just use an isolation and then do a Clements introduction and get rid of that carbon eel and we're done. Okay, So let me show you guys the true The best way to prepare n poeple. Benzino, if you guys don't remember, if you see that little end in the front, that just means it's a straight chain. So we're trying to get n straight Chain three carbon benzene. What we could do is we could isolate first. That's going to give me a mono substituted product that looks like this. It's a key, Tom. That's not what we want. But wait, we've got Clements introduction. What does Clements introduction do? It zaps that carbonell completely. So I'm gonna take myself out of the screen. What I wind up getting is just and Pro Bowl benzene, which is what I wanted. Okay, so this is why we're gonna really emphasize that isolation is better than calculation. And any time you wanna add in our group, try adding it with an isolation first and then doing a Clemmensen because it's probably gonna be more efficient. Okay, so that's it for this video. Let's move on to the next.