21. Enolate Chemistry:Reactions at the Alpha-Carbon
Enolate Alkylation and Acylation
21. Enolate Chemistry:Reactions at the Alpha-Carbon
Enolate Alkylation and Acylation - Video Tutorials & Practice Problems
On a tight schedule?
Get a 10 bullets summary of the topic
1
concept
General Reaction
Video duration:
1m
Play a video:
Hey, guys, in this video, I want to discuss easily calculations and isolations. So, guys, there's really nothing tricky to this reaction. As long as you can draw in a late you could do in anal a calculation, because all it is is that you're either exposing and until eight to an alcohol. Hey, lied. Okay? Or you're exposing and immolate to an acid chloride. Okay, What happens is the base grabs one of the protons in the Alfa Carbon. You make a negatively charged in a late and that does a nuclear feel like attack on either the alcohol. Hey, lied or on the acid chloride. Okay, if you use an alcohol. Hey, lied, then This would be my product in Alfa calculated carbon. If you use your acid chloride, then you're gonna wind up getting an ace elated carbon. So you get a beta die carbon okay, within our group, depending. Okay, so that's it, Guys, this is a very easy mechanism to understand. Very easy reaction to understand. So let's move on to the next part of the page.
2
concept
Directed Reactions
Video duration:
4m
Play a video:
This brings us to directed reactions, guys, because the mechanism that I showed you above, even though it's great, very easy to use it on Lee works with symmetrical key tones. It only works when there's only one type of Annaly possible. But what happens if you have in a symmetrical key tone? Okay, that means that you would theoretically have more than one mutilate possible. For example, take this key tone into consideration. I could get the red easily on the more substituted side, or I could get the blue inlay on the less substitute side. Would I get both? Would I get our groups forming on both sides? No, this is something that we have to answer using directed reactions. Well, it turns out guys that you can use different bases to direct the direction of the pro nation of the Depo Nation to make the equally okay. And guys, this is a concept that should be familiar to you guys because we've used it before. This is simply a thermodynamic versus kinetic control reaction. Okay, so the thermodynamic product, let's just review, is gonna be the one that's more stable right? In this case, since there's an anally Inter mediated reaction. It's gonna be the one that has the lowest overall energy or the most stable easily. Okay, I'll show you how to determine which was more stable in a second. The kinetic product is the one with lowest activation energy. Or that just means easiest to make. Okay, so how do we know which Italy is stables? More stable. Will remember that in Italy goes through to resident structures. Right? One of the resident structures is like this but another resident structure. It looks like this. Right? Well, look at that. One of the residents structures has an Al Keenan. So the way you determine which one is the most stable, Italy is by the most substituted Alfa Carbon. Okay, Why? Because and really, Guys, I'm sorry. I'm drawing that on that side, and I really should have drawn it on the side with the actual read one that's gonna be over here. Okay, So if you want I know you hate me right now, but you can pause the video and redraw that on this slider if you want, or you could just drawn there. Okay, So the one of the most substituted Alfa Carbon is gonna be the most stable. Okay, so that means that the red one would be my thermal dynamic control. Okay, because the one that is gonna it has the most are groups on the awful carbon. So that means it's gonna have the most are groups on my double bond. And that's what makes a double unstable. Remember that double bonds are stabilized through our groups. Okay, Now, what makes a kinetic usually is the easiest to make, or that's gonna be the least substituted because it's less hysterically hindered. Okay, so these are the competing themes here. Okay? So specifically, how do we choose one or the other? Well, if you want the blue in late, you choose a bulky base like L d. A. Okay, so l d is the most popular one in this section. You could also use turkey talk side. Okay. So bulky base is going to favor the kinetic product is the easiest one to make, whereas a small base. Okay, so, for example, anyway, H is gonna favor the thermal dynamic because it's not gonna have trouble getting into that spot to Deep Protein E. And it's gonna make the most stable easily overall. Okay. So you would determine which side you substance you by looking at your base and then using that mainly to react with your electric file, whether it be an ocular Hey, lied or in acid chloride. Okay, awesome guys. So in the next video, I want to talk about how this applies to Esther's.
3
concept
Enolates of Esters
Video duration:
3m
Play a video:
guys so really quickly. Esters can also be calculated and isolated. The only catch is that you need to use L. D a. You can't use any other base you can't just use like hydroxide. Why do you think it would be a mistake to use or which negative on an Esther. Can you think of a reason? So, guys, if you use always negative on an Esther Well, you're actually going to get is Ah, hydraulics, Sis, you're gonna wind up getting a car, Boxley. Okay, on that would be like a n A s reaction. You don't want your base to react with the alcohol group? Same as if I used Let's say O. R one, right. If I used in Alcock side base with an are different from the army alcohol group, I'm going to get a transit certification. I don't want that to happen. So what we do is we use a non nuclear feel like l d is considered a non. Let me draw it for you really quick. L d a. In case you haven't seen it in a while. Nitrogen isopropyl isopropyl with the, um this is considered a non new Cleo feel like face. Okay. Why? Because it has a very hard time. Can't Dhoni. It's electrons. Oops. Electrons. Okay, Can you see that? Perfect. Okay, sorry. My handwriting sucks down there, but L d A is a non nuclear Philip basic Can't donates electrons, so it's not gonna be able to attack this carbon. Instead, it just reacts as a base and pulls off and alfa hydrogen see? So by using L. D a. We strategically make the in Italy, and we don't have to worry about any types of, um, carb oxalic acid derivative reactions. Now, by the way, guys, if you haven't studied carb oxalic acids yet or if that wasn't your forte, don't worry about that. I don't really care that you know all the details here. If this is the first time you ring well, transits, verification or any s or any of that, just focus on the point. The point being use L d. A. For reasons that you don't understand yet use L. D. A. And later on, when you get to Carlos, look at the derivatives. It will make more sense. Okay, So l d a makes until eight. And then you would then do your attack on the alcohol He lied or the acid chloride and you would get your products. Either Oh, are within our group or oh, are within a silk route. Makes sense. Awesome guys. So pretty. Pretty easy, page. Nothing too crazy. Here. Let's move on to the next page.
4
Problem
Problem
Determine if the reaction is thermodynamically or kinetically controlled
A
Kinetic
B
Thermodynamic
Do you want more practice?
We have more practice problems on Enolate Alkylation and Acylation
Additional resources for Enolate Alkylation and Acylation