The E1 mechanism is similar to E2 in that you get an elimination product, but the path to get there is completely different. It’s important that we understand how it’s different from E2.
Drawing the E1 Mechanism.
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So now I want to talk about a mechanism that competes directly with the s and one mechanism, and that's called the E one elimination mechanism. All right, so if I were to sum up the entire mechanism in tow one sentence, what I would say is this e one occurs when a week nuclear file reacts with an inaccessible leaving group. So let's just start right there. Okay? Do you guys remember another mechanism that we talked about that had similar conditions? Yeah, right. The S and one. Let's talk about the nuclear fall apart. First we said that s and one is favored. With what type of nuclear file? Strong or weak. Well, remember that strong favored the s and to an e two. Okay, So week is gonna favor s and one and e one. Why? Because remember, that s and one I'm sorry. Remember that. Ah, weak nuclear file would not start the backside attack. First. It would wait for something to happen. Okay, So remember that the weak nuclear file just kind of was chilling and just sitting back and waiting for something to happen. Well, then, what's the other condition? The other condition says that it's with an inaccessible leaving group. Inaccessible really is just another word for tertiary, right? It's basically, uh, there's many are groups is possible. Why was that good? Well, the reason that's good is because remember that tertiary alcohol hey, leads would make really good Carvel Catalans. Remember that Carvell Catalan was the rate determining step for S and one. Is this all kind of coming back to you guys? Well, it turns out that the same condition is also good for e one e one, also like savin inaccessible, leaving group. So if we have the same exact conditions that are good for both mechanisms, how do we know when one is gonna happen or the other is gonna happen? And it turns out we don't. So it turns out that these same exact conditions are gonna also produce beta elimination in two steps. What that means is that what we're gonna find out is that s n one e one always compete with each other and they're almost impossible to separate. What that means is that every time you see an s n one reaction, remember, I taught us and one e one is also occurring and you really can't do much to stop it, OK? And that's one of the messy things about these reactions is that they're often gonna lead to a mixture of products and synthetically That's not very useful for us. Okay, when I say synthetically, that's a word I'll use a lot more later. As we get into or go to synthesis is a huge end goal of organic chemistry. Eventually, what you're going to be doing, get excited. You're gonna be trying toe synthesize a target compound. Your professor is just gonna be like, Hey, make this and you're just gonna have a list of re agents and you have to put them together, okay? And sn one. Anyone aren't very hopeful for synthesis. The reason is because you get a mixture of products and that's bad because then you don't know exactly what you're getting at the end. Okay, so let's just go ahead and talk about this mechanism and see how you could get the S and one or the E one. Alright, so here I've got as you'll see a tertiary alcohol, he lied, and the first step is gonna be the same identical for both of these reactions. So what's that first step? Can you guys tell me? Is it backside attack? No. Okay. Why? Because my new cliff isn't strong, so it can't initiate anything. Remember, it's not one of those arrows. It doesn't do that. So it's just gonna wait around. What actually happens is that the leaving group leaves by itself. Remember? That's part. It's kind of weird, but it's associates. What that's going to do is it's going to give me a new intermediate that looks like this single bond h is exactly the same. H h h. Okay, but now what I have is a carbon Catalan. That carbo Catalan came from the fact that the X just left by itself without getting anything in the turn. So electrons air leaving, OK, and then finally see how I have r one and r two. Those would still be here is well, so I'd have are one and are too cool. So it doesn't matter which one you put where because there's a caramel cat and so you don't actually know what you would get. Okay, so now what? Well, it turns out that this carbon Catalan is gonna do what next? The nuclear. I was going to react with it. Right? Cool. So my new cliff, I would want to react with it. And the first thing you would think is that the nuclear fall has electrons to give away. I remember it doesn't have a negative charge, but it does have a lone pair, so it could attack directly my Carvel, Catalan. And it turns out that that is gonna happen. That nuclear felt is going to directly attack the cargo Catalan, and that's called the S and one mechanism. So what we would do here is we would draw the s and one product and the S and one product would just be that I have now to our groups again. Okay. And I would have thes h is exactly the same. Okay, but then I would get a nuclear file attached to wherever that carbon was. Okay. Now notice that I had R one and R two. Okay, so those are different. Does this make a Karol center? Yeah, most likely it does. So what that means is that remember that I would actually get two different products. I would get one in an steamer, and then I would also get another in an summer. Well, let's say that this are one was faced towards the front, and this are too was faced towards the back. I would also get the other Indians humor where I have the nuclear file facing the same way. But now I have are two in the front and are one in the back. Is that making sense? I'm just gonna leave this a ch three. All right, So remember that whenever you make a Carl center, you have rasam ization. That means that you get 50% of each, and that's exactly we would get for s and one. Okay, But now we know that's not the only thing that's going to take place. There's also another mechanism that's going to compete with this, and that's the E one. Okay. And what the E one is going to do is it's going to say, you know what? I could direct I could attack the carbon County and directly, but that's too boring. Why would I want to do that? Okay. Actually, I don't know exactly why it doesn't, but it's also going to say you know what? I am a pretty good nuclear file. But I could also act like a base. And what basis do is they pull off protons. Remember that nuclear files and bases, many times they're similar. So it's going to say, Well, let me just pull off a beta proton. And then once I pull off that beta proton Aiken, put these electrons into that bond there and satisfy the carbon Catalan. This is also gonna happen, and that's called the E one mechanism. So it's gonna be competing with the S and one at the same time. So what that means is that now what we're going to get is a double bond that has h is now only two. H is not three Onley too. But now it has a double bond. Does that make sense, guys? So we would not only have two different substitution products because of the regime IQ part, but we would also have an elimination product as well. Okay, on top of that, remember that, um, elimination products may yield several products. In this case, I would only have one because I only drew one set of data hydrogen. But if I had more beta hydrogen, I could react with all of those. Okay, so one of the reasons that this is so messy, it's because you have the possibility for upto five different products at times because you could sometimes get two different substitution and then three different eliminations, depending on what your leaving group looks like. And for synthesis, that's really bad, because the last thing a professor, the last thing a researcher wants to do is to separate a bunch of molecules that are very similar. They're gonna be very difficult to separate from each other. And the really last thing that you wanna dio is trying to make a target drug or a target molecule and then have other things mixed inside. Okay, imagine if you were buying some pills from Walgreens and the chemist was lazy and he decided to include an anti MERS in there or decided to include other types of double bonds. You could die. All right, so that's why you have to be very careful when you're doing synthesis toe only get 11 product, and that's not what we're doing here. All right,
Summary: A neutral nucleophile reacts with an inaccessible leaving group to produce elimination in two-steps.
Understanding the properties of E1.
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So now you guys know to expect s and one and the one at the same time. Let's just go ahead and fill out some really quick facts about this. And I expect this part to be really easy for you guys, because we've already done this for s and one. And it turns out that the one in E one stands for the same thing. E one stands for elimination Union molecular. Okay, that means that in terms of rate kinetics, everything is gonna be very similar. So do I want a strong or a weak I want a week because I don't want to do I don't want the nuclear fall to attack first. I wanna make my leaving group. Okay. Is my leaving groups substituted, Highly substituted or un substituted, highly substituted because this is going to make good carville cat ions. Okay, so that's what I want. My transition state or my reaction coordinate would be an intermediate, not a transition state, because intermediates, carbo caravans or intermediates, This would be a two step reaction because I have a slow step in a fast step. What's my slow step? My slow stuff. Just you guys know right here. That's my slow step. Okay? And then my fast step is once I've made that Korbel cat ion, I could either attack it directly with an S and one or I could do a beta elimination with an e one. But regardless, both of those air fast steps, because once a carbon county and is made is very, very easy to attack it. Cool eso then a little bit more. The reads as I told you guys would be uni molecular. What does that mean? Do you guys remember? It's the same thing that I meant in S. And one. What that means is that if I increase the amount of nuclear file, let's say I have 10 times the amount of nuclear file. Will that increase the rate of my reaction? No, because it's like I said with that analogy, where the factory makes Carvel Catalan's one at a time. And then there's, like, tons of boxes just laying around that someone's packing, making boxes. Okay, in order to ship the product, I don't need more boxes. I need more carbon Catalans. So if I were to double the amount of boxes that I have, I'm still not gonna have more products to ship out, okay? And it's the same thing with this. The only thing that changes the rate is how fast I could make carbon cat ions, which that's gonna be the leaving group, not the nuclear file. So that means that my rate is gonna be just believing group. Okay? And then finally, the stereo chemistry is gonna be I'm just gonna put here. Doesn't matter. Okay. Remember that. Oops, that's ugly. Remember that you had antico planer for E two. Anti complainer does not apply for anyone. Why? Because remember that for e to my leaving group was still attached and then had a beta hydrogen. But in e one, guess where my leaving group is? It's out in solution. It already dissociated because remember, you made a positive charge on that positive charge. It doesn't matter where it gets attacked from. It doesn't have any stereo chemistry that it needs. So you don't worry about Antico planner. So if you want even to be more clear, does put no antico planner. Okay, so I hope that makes sense to you guys Now, Now you know that your mind is filled with a bunch of mechanism. So we're gonna do some practice of this, and then later on, obviously, I have to teach you guys when you use which mechanism. And that's gonna be the whole purpose behind this awesome flow chart that I'm going to show you guys at the end of today's lesson. All right, so let's go ahead and move on to the next video.