Hydration Reaction - Video Tutorials & Practice Problems
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concept
Symmetric Alkene Hydration Concept 1
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In hydration reactions, we have the acid catalyzed addition of water to an alkene and it produces an alcohol. Now, in this reaction, we're going to add one H and 10 both coming from water to one pi bond. If we take a look at the overview for this reaction, we start out with an alkene and we're gonna add to it, this water molecule to do that. We need to utilize sulfuric acid which acts as an acid catalyst to get the process going. Now, if we take a look at the alkene, both of these double bonded carbons are the same, the alkene is symmetrical. They both are connected to one carbon and one H. That means that the H and oh can go to either of those double bonded carbons. H goes to 10 goes to the other one. Later on, we'll see what happens when we have an al king that is not symmetrical. Where would the H go in that case, where would the oh go? Right. So if we take a look, I'm gonna add the H onto this double bonded carbon, we're gonna break the double bond in order to add it. So at the end, we're not gonna have a double bond within our product and then we have our oh added to the other one. So here this produces our alcohol. So just remember a hydration reaction, hydration means we're adding water. Here we're adding in a water molecule to an alkene in order to produce an alcohol.
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example
Symmetric Alkene Hydration Example 1
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Complete the following hydration reaction. So here we have a cyclic alkene, we're having water and we're using sulfuric acid as our acid catalyst. Now, one thing to note before we do this question is that instead of H two, so four, sometimes you might see them write H plus H plus serves the same purpose as H two. So four, the whole purpose of this acid cyst is just to provide an H plus ion to help the process go, right? So you might see H2O with H plus, we might see H2O with H two. So four. Now, if we look at our alkene, we have a carbon here and a carbon here right now, we see them both making three bonds, but carbon needs to make four bonds. So there is a hydrogen that is not visible. If we take a look at both alkene carbons, they both are connected to what one carbon and one hydrogen, they both are essentially the same, this is symmetrical alkene. That means that the H and oh can go to either one of those alkene carbons. So I can draw this as my product. The H I say goes up here and the oh goes over here or you could say that the oh goes up here and the H goes here, it's, they're the same molecule. I'm just showing you that H and oh could go to either double bonded carbon in this case because they're both have the same type of, of substitution. They both have the same type of car number of carbons and hydrogens connected one another. Right. Later on, we'll see what happens when we have a non symmetrical alkenes because then it does matter where the hnoh goes in this instance, it really doesn't matter. Right. So, either one of these is an answer that you could show and it would be correct. Right. So we've gone from an alkene to our alcohol product.
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concept
Markovniko's Rule Hydration Concept 2
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Now, the addition of water in asymmetric alkenes follows Marko Niko's rule. Now, under Marko Niko's rule, we're going to say that our H Adam is added to the carbon, the alkin carbon that possesses more hydrogens. So more HS and we're going to say here that the oh is added to the alkane carbon with fewer HS fewer hydrogens. If we take a look here at our hydration reaction, we're starting out with a, an alkene that is not symmetrical, it's not symmetrical because the alkene carbons have different number of hydrogens attached. The one here only has one hydrogen directly attached to it and the one here has two, we're gonna have water attaching to it and we have either H plus or sulfuric acid being the catalyst to help this process go. So if we take a look, we're gonna follow Makoko rule, which says that the H should go to the alkane carbon that has more hydrogens. That would mean that it will go to this carbon here. So we add an H to that one and then oh will go to the one with less hydrogens directly attached. So we're talking about this one. So oh, which would add to this one, this would represent our major product because this is the product that's formed by Markov Niko's rule. Now, the minor product would be the one that's not doing what it's supposed to do. It's doing the opposite of Markov Niko's rule in this instance. That will mean that h actually went to the one with less hydrogens or fewer hydrogens. And then, oh for some reason, went to the one with more. Now, when this reaction happens, a vast majority of the product is this high percentage of it is this and you'd make a very small percentage, maybe sometimes less than a percent of this minor product here, right? So just remember when your alkene carbon is not symmetrical, meaning the double bonded carbons don't have the same number of hydrogens utilize them are knik rule to figure out which one will be your major product.
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example
Markovniko's Rule Hydration Example 2
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Complete the following hydration reaction. If we take a look here, we have our two double bonded carbons. This one and this one, the one on the left, we see it making 123 bonds, carbon needs to make four bonds. So there is a hydrogen that's invisible. The other double bonded carbon we already see making 1234 bonds. So it has no hydrogens at all. Now, this is a asymmetric al king because the double bodied carbons have different number of hydrogens. So we're gonna follow Markov's rule to determine the alcohol that will form. Under Mark Koko's rule, hydrogen should go to the double bonded carbon with more hydrogens. So the H would go here and it'll be right next to the other h that was already present and then oh will go to the double bonded carbon that has fewer hydrogens, the one on the right. So I'll wait for that here. So this would represent the alcohol that we formed. Now, if you wanted, you could erase these hydrogens and understand that they're there. They're just not being shown. So this would be the best way to show this particular alcohol when omitting those invisible hydrogens. So this would be our final answer.
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Problem
Problem
Draw and name an alkene that would be used to produce the following alcohol through a hydration reaction.
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D
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Problem
Problem
Providemajor and minor products for the hydration of 4-chloro-3-ethyl-1-hexene.
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