What alkenes might be formed by dehydration of the following alcohols? If more than one product is possible in a given case, indicate which is major.
b.

Question

What alkenes might be formed by dehydration of the following alcohols? If more than one product is possible in a given case, indicate which is major.

b.

Accepted Answer

Hi, everyone. Let's look at our next problem. Consider the following alcohol that upon acid catalyzed dehydration yields an alkene if more than one product is possible, only provide the major and our alcohol is two methyl cyclohexane all. So we'd want to start, of course, by drawing our alcohol. So we have a cyclohexane all. So a six carbon ring note that it's not a benzene ring, it's just a six carbon ring with single bonds. And then we have our alcohol group on there. Now it's two methyl cyclohexane. All the alcohol group would be the priority substituent. So that would be considered carbon one that it's on. So our methyl group will be next to our alcohol group on an adjacent carbon. So we can recall that in a dehydration reaction, we lose our oh group and a hydrogen from an adjacent carbon molecule or adjacent carbon. Adam, excuse me. So in this case, we have two adjacent carbon atoms. So let's draw the hydrogens that are adjacent on those adjacent atoms to see which ones can leave the carbon two with the methyl group has one hydrogen, carbon five on the other side, has two hydrogens on it. So these are our hydros that are hydrogens that are available for this dehydration reaction. So let's think about what will result we're in an acidic environment. So we've got plenty of protons floating around. So we know that for our, as our alcohol group to be eliminated, one of our lone pairs on the oxygen combines with one of those protons, it protons this alcohol group. And then as a result of this proton alcohol group, the electrons that form the bond between the alcohol and its carbon join the oxygen and cause it to leave as water. So we have water is leaving and we form a carbo c. So we've got our six carbon ring, the oxygen is gone, got our methyl group still there. So we still got our hydrogens present. But now we have a positive charge on the carbon where the alcohol used to be. And of course, carbon doesn't like having a positive charge. So the end result will be one of our pairs of electrons in ach bond, we'll form a double bond with that positive charge. So that will give us two possible products. And we recall that we have a sort of equilibrium existing here between the alkene and the carbo cion. So we can lose a hydrogen from carbon five, which will give us a double bond between carbon one and carbon five. Or we can lose a hydrogen from carbon too and give us a double bond between carbon one and two. Well, don't forget that our question told us if more than one product is possible, only provide the major, which is the major product here. Well, to determine that we are guided by Zaitsev's rule, which says that if two or more than one alkene isomers are possible, the more substituted alkene is favored. And that's because again, we have this equilibrium between the carbo ion and the alkene, The more stable the alkene, the more likely our compound is to stay in the alkene form. So when we look at our two alkenes here, we see, we've got the second product where the alkene is between carbons one and two is the more substituted since we have that methyl group on carbon two. So our second product, our two methyl cyclohexane is our major product here due to that being the more substituted al Keen. See you in the next video.

What alkenes might be formed by dehydration of the following alcohols? If more than one product is possible in a given case, indicate which is major.
b.

Verified video answer for a similar problem:

Key Concepts

Dehydration Reaction

Zaitsev's Rule

Regioselectivity

What alkenes might be formed by dehydration of the following alcohols? If more than one product is possible in a given case, indicate which is major.b.

Verified video answer for a similar problem:

Key Concepts

Dehydration Reaction

Zaitsev's Rule

Regioselectivity

What alkenes might be formed by dehydration of the following alcohols? If more than one product is possible in a given case, indicate which is major.
b.