The following alkenes can be prepared by dehydration of an app...

Question

The following alkenes can be prepared by dehydration of an appropriate alcohol. Show the structure of the alcohol in each case that would provide the alkene shown as the major product.

b.

Accepted Answer

Hi, everyone. Lets look at our next question, identify the structure of the alcohol that would react via dehydration and produce the alkene below as the major product. And we have an alkene structural formula here or line structure, I should say not structural formula. And Earl Keen has three methyl groups and one propol group. So we need to identify which structure would produce this product via a dehydration reaction. Well, let's just recall what's going on. And in the dehydration reaction, we have two carbons with a single bond between them and some sort of R group on either side or multiple R groups. And you have an oxygen group, L drawn red on one carbon and you have a hydrogen group, I'm sorry, not hydrogen group, a hydro hydrogen atom on the other side. And this molecule reacts with acid. So for instance, H two. So four and the alcohol group and the hydrogen are both eliminated, producing a double bond where the ox, the alcohol and hydrogen were eliminated and water. So there is a rule about the major product being the more stable alkene with the more highly substituted double bond. But in this case, we see that our double bond has four substituents. So both carbons in it have two substituents. So in that sense, we need to keep in mind that our alcohol group could be on either one of the carbons. So we have two possibilities for an alcohol that would yield this product. So what would they be? Well, in one case, we'd look at, so let's look at our carbons and our double bond, I'll highlight in blue, the first Carmen and the highlight in red, the second carbon. So we know we could have our alcohol group on the first blue carbon. In that case, we would have the structure that we see in choice B where we have our blue carbon. So that's match that up here. And you see it as the two methyl groups like our alkene and an oh group highlighted in blue there. And then we have our red carbon that was in the double bond. But we see that the original reactant had a single bond and it has a methyl group and a prophyl group. So it would have had a hydrogen adam that got eliminated along with the oh to generate those double bonds. So choice B is going to be one correct answer, but we can't have more than one because we could have had that alcohol group on the other carbon that went on to form that double bond. So what does it look like if it were on the other carbon. Well, we see we would have had are first carbon with two methyl groups that will still look like that because it would have the hydrogen atom that gets eliminated. So that is understood on the structure. And then now we see in this case, we have the alcohol group on the second carbon. So it has a methyl group and a prophyl group and an alcohol group. So the alcohol and the hydrogen get eliminated to yield the double bonded alkene. So we see that choice A can also be the structure that could yield our original molecule by dehydration. Now, let's look at choice C. Well, choice C is not our answer because it has the alcohol on the very first carbon not on a carbon in the double bonds. So this one would not be the case because the carbon that the al alcohol is on is not in the double bond in the keen. So choice C is not correct. Therefore, choice. Eb and C is not correct. We know that both A and B are possibilities. So our answer will be choice D. So the structure of the alcohol that would react via dehydration and produce the alkene below is choice D A and B. See you in the next video.

Struggling with GOB Chemistry?

The following alkenes can be prepared by dehydration of an appropriate alcohol. Show the structure of the alcohol in each case that would provide the alkene shown as the major product.
b. <IMAGE>

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Alcohol Reactions: Dehydration Reactions practice set

Struggling with GOB Chemistry?

The following alkenes can be prepared by dehydration of an appropriate alcohol. Show the structure of the alcohol in each case that would provide the alkene shown as the major product.b. <IMAGE>

Watch next

Alcohol Reactions: Dehydration Reactions practice set

The following alkenes can be prepared by dehydration of an appropriate alcohol. Show the structure of the alcohol in each case that would provide the alkene shown as the major product.
b. <IMAGE>