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Video Solution: A hydroxyl group is a somewhat “smaller” substit...

Problem

A hydroxyl group is a somewhat “smaller” substituent on a six-membered ring than is a methyl group. That is, the preference of a hydroxyl group for the equatorial orientation is less pronounced than that of a methyl group. Given this information, write structural formulas for all the isomeric methylcyclohexanols, showing each one in its most stable conformation. Give the substitutive IUPAC name for each isomer. 

Video Transcript

Hey everyone. So, in this problem we're going to be giving all the isomeric methyl cyclohexanols and notice that we're going to draw them in the chair conformation. So, in the chair conformation our questions they did that the OH group is going to be smaller than a methyl. Now, in chair confirmations we know that equatorial and going to be more favored for a bulkier substituent such as our methyl group, so we can start out with the easiest one by drawing OH here, axial and then drawing our methyl group equatorial and the name of this compound would be 1-methyl cyclohexanol because this is a six membered ring, okay? Now, there's going to be a ton of different isomers that we can draw, so let's actually paste them in right here, I have all these different share confirmations, then we're going to be going through all the different isomers. Alright, so let's start out at the top. Now, we're going to be keeping the OH at this position at all times, so let's start now. We have our OH there and I'll just move the position of our methyl group, so let's move it actually to this carbon and this too. Alright now the first one we can actually have it cis, we're going to be keeping it equatorial at all times, so we can have it cis, right? The name of this compound would be cis-2-methyl cyclohexanol, we need to keep that methyl group equatorial at all times, so we have to actually keep our methyl facing that direction, but what we can do is change the position of our alcohol and make it face down equatorial and then with this now would be trans because they're facing the opposite direction, one's down one's up, trans 2-methyl cyclohexanol.Now, what do you think we're as do for the next one? Well, a little bit of a hint, are OH groups guys they add at this position? right? this is where our OH is going to stay at all times but it could vary whether it's axial or equatorial but remember, methyls are always going to be equatorial, so what, and these two are going to add our methyl group one more carbon away, so there's going to be a 1, 3 relationship between our two groups and what do you think is going to be our last one? Well, they're going one more and that would be to be 1, 4 because remember this would be 1,2, right? 1,2 relationship and this would be 1,3, okay? So they would be repeated if we did it there, so let's get started, we're going to have our OH group, in the next one we need to make it trans and cis, so let's star with the cis one. So, our methyl is going to face equatorial, which would be in this direction. So, in order to make our OH cis it's going to face down and the next one we're going to keep our methyl equatorial but now we're going to make it a trans relationship, so we're going to include our OH up, okay? So, go ahead and try to name those and now we're going to move on to the next one just to show how we can make it cis and trans again and I encourage you to do this on your own, so let's start equatorial, here would be in this direction, right?

Now we need to look a cis and trans relationship. So, we start with cis first, what does that mean? means our OH gets to face axial, right? Because that's cis, this would be trans, so let's go ahead and name our last three compounds. So, what would be the name of this one? Well, we have now a, what relationship? cis, they are facing in the same direction, this one was trans the top one was, what? cis. This one was trans and all we need to do is just include the position of our group, so this was going to be cis 4-methyl this one's going to be trans 4- methyl and then cyclohexanol, this one's going to be cis, what? and trans, what? 3, right? And then of course we can include the whole name if we want, we know it's going to be methyl and then cyclohexanol, okay? So, for all of these is going to be the same thing. So, methyl cyclohexanol, let's just move these so I can fit everything in, we have OH and then the name is going to become methyl cyclohexanol, same thing here, cyclohexanol, and I'm going to jump out of the page really quick to do our last two. This one is methyl cyclohexanol and methyl cyclohexanol, okay? And our of course first compound that we can draw was that 1-methyl cyclohexanol and then changing the position of where our methyl was, giving all of these shares and more stable conformation with our methyl equatorial. Alright, so hopefully that made sense, let me know if you guys have any questions.

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