Alkyne Hydration - Video Tutorials & Practice Problems
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Alkyne Hydration
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back when we talked about how we could add groups. Two double bonds. We discussed how there were three different ways. Toe add water, tow a double bond to Macon alcohol. Well, it turns out that if we add water to a triple bond, we still are going to get that alcohol. The thing is that we're going to get a slightly different product instead of just having a single bond with an alcohol. We're now gonna have a double bond with an alcohol attached to it. And even though that sounds like a very minor difference, that's actually gonna translate into a huge difference in the functional group that we get afterwards. All right, so let's go into this right now. This is gonna be the hydration of triple bonds. So it turns out that any time that you make a vinyl alcohol, that's the name of basically having an alcohol directly on a double bond that is going to react very uniquely, it's not going to react like the addition reactions that we saw with double bonds. In fact, this is going to do it a phenomenon called Todd Memorization. Now, this is a phenomenon that we're not gonna fully understand the mechanism for until or go to. So it's kind of, you know, unfortunately, we have to talk about it now, But I'm just gonna give you guys like a really quick, fresh refresher on what this is. So you guys know what Todd memorization is? So basically, if I were to summarize it, I'm not gonna teach you the full mechanism, because that would be a whole separate lesson. But all you really need to know is that they're gonna reversible e swap the position of a hydrogen. Okay. And a pie bond. Okay, so this is what I'm saying. Any time that you make a vinyl alcohol, this is something special. This is not a regular alcohol. This is an alcohol that is now subject to a phenomenon called Todd Memorization. So here, I'll show you here would be an alcohol that's directly attached to a double bonds Is vinyl alcohol and through the top memorization process that I'm not going to show you. The mechanism for this is going to turn into ah, completely different functional group where basically my double bond is gonna move over here. My h is gonna move down here So this year on a switch, places and what's gonna wind up happening is that you get ah, carbon Neil formed. And instead of this being a c H two now, this is gonna turn into a C H three. So what winds up happening is that this turns from a vinyl alcohol toe? A key tone. Alright, How did that happen? Like I said, unfortunately, it would take me 20 minutes to explain this whole thing to you. So instead, I'm just gonna tell you guys to memorize that a double bond and a hydrogen switch places anytime they have a vinyl alcohol. All right, now, we do have some fancy words for this because this is its own thing. Basically, when it's in the vinyl alcohol phase that's called the Enel. All right. And that makes sense, because in stands for Al Keen, all stands for alcohol. So basically, whenever you have an alcohol on the AL Keen, that would be called in anal. Well, the Enel rapidly taught, um arises to the Keto form. The Keto form is just the key tone or the alga hide that's produced after Todd Memorization takes place. Now what? You notice is that I didn't draw these equilibrium arrows evenly. This is This is a phenomenon that's constantly in equilibrium, but one of the arrows is much bigger than the other. And that's because it turns out that the Keto form is gonna be favored in almost all cases highly favored over the final form. So what that means is that immediately upon making any vinyl alcohol or most vinyl alcohol's, I can expect it to rapidly transform into the Keto phase. And the Keto side of the equilibrium looks like a key tone or in Alba hide. So basically, the whole gist of what I'm trying to say is that any time that you hydrate a triple bond, you're actually going to get a key tone or an alga hide as the product, all right, and it's through this process of Todd memorization now, exactly which ones do we get? Let's go ahead and look at each specific regent. So there is oxi Mercure ation of all kinds, Okay, and there's hydro beret shin of all kinds. So when we do an oxy Mercure ation of al Kind, what we're really doing is we're doing it. A Markov Nankov addition of alcohol. Okay. Remember that Oxy Mercure ation is the most popular way. One of the most popular ways. Toe Adam are cop nick off alcohol toe a double bond. Well, the same thing applies for a triple Bond is. Well, what that means is that if I have to sites, I have, let's say the blue site and the red site, and I'm trying to figure out where the alcohol is going to go. It's gonna go in the more substituted position. So I would expect that after an Oxy Mercure ation, I'm gonna get alcohol right here, okay? And the more substituted position. Now notice that I put the Oxy Merck re agents down here, but I also included h over h 20 Do you guys remember what that was? That's hydration. Okay, this would be an acid catalyzed hydration. And just so you know, both of these create Markov knock off editions, right? Both of them favor the Markov Nick off alcohol. So actually, I can use both of them. Even though Oxy mark is maybe more commonly used, hydration is still a great choice. Okay, so both of these re agents really leads the same intermediate structure, which is gonna be this evil. All right. Are you getting that? So far? The reason I'm calling it an Enel is because now I have a more cognitive alcohol on a double bond. But we know that it's not going to stay like that because Enel's air not stable. They like to Tottenham arise. So, after the top memorization process, what's the product gonna look like? Well, the product is gonna be the same ring. Okay, But now, instead of having a single Bonds Oh, I'm gonna get a double 120 instead of having a double bond to the carbon, I'm not gonna have a single bonds of the carbon. So it turns out that the product of Oxy, Mercure ation or even hydration is going to be key tones. Okay, so any time that I'm hydrating market Nick aww hydrating a triple bond, I'm going to get a key tone. Is the product okay? Now, what part of this mechanism should you be able to draw the first part? The second part. You are fine. Just to say Todd memorization. Just label it and then draw the product. Okay? Like I said, I'm not going to teach you that full mechanism till we get to or go to. Alright. But for right now, you know at least the general idea of what's going on. All right, so remember that we had three different ways at alcohol. We had hydration. We had Oxy, Mark. We had one more, and that was Hyderabad oration. Remember? What was kind of interesting about hydro gration was that it did everything opposite hydro operation is actually gonna be anti Markov Nankov addition of alcohol. So what that means is that if once again, I have the blue site and I have the red site, which one is it gonna add to? Well, it would actually add to the less substituted position. So it ad right here. Okay, so once again, notice that I'm getting an email. I'm still getting a vinyl alcohol. The difference is that it's just in a different position. Okay, Now, notice my re agents really quick. Just noticed that I said ph three or on other boron source. That's because hydro operation there's a lot of different boron sources that your professors could use. So you just have to be aware of the one that your professor likes to use. Okay? And then obviously the bottom part was the oxidation step. So I got the Enel. How do I figure out what the product looks like? Same process. I'm going to switch the position of the double bond and the H. So what that means is that in my final product, what I'm going to get is now, instead of a double bond there, I'm just gonna get a single bond. And instead of a single one to the oh, I'm gonna get a double one to the O. Okay. So what this means is that where did the extra h go? The extra h went here because right now there was only one h here. And now there's gonna be two ages. There's that original age. And then there's that extra age that extra blue eight short ever. Was this a trade here and it transferred? Okay, so now notice what kind of molecule this is. I just drew a terminal carbon Neil, This actually has ah hydrogen at the end. This is actually gonna lead to the formation of Alba hides. Okay, so when you do a Markov knockoff edition of water, that's gonna be a key tone product. Okay? When you do an anti Markov knockoff edition of water, where you're gonna lead to is an anti Markov nick off alcohol or Enel, which then turns into an alga hide. Now, notice that in general this is still called the Keto form. Okay, if you were to say, just in terms of Todd Immers, this is the anal totem. Er, this is the Keto totem er, but this specific molecule happens to be an alga hide because the carbon was right at the edge, and it has one h on it. Okay, so just something that you guys need to be aware of. It's something that could definitely come up. So you guys just need to know what's going on. All right? So I hope that made sense. Let me know if you have any questions.
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