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Solution: myo-Inositol is a polyol (a compound containing many OH grou...

Question

myo-Inositol is a polyol (a compound containing many OH groups) that serves as the structural basis for a number of secondary messengers in eukaryotic cells. Draw the more stable chair conformation of myo-inositol.

Video Transcript

Alright guys. So, here's our compound, it's a six membered ring and at every carbon there is an alcohol group and we need to draw the most stable chair conformation for it, right? So we're going to start by first numbering all of our carbons, so this is 1, 2, 3, 4, 5 and 6 and then what we can do is we can draw a chair for this. Now, I chose the chair that looks like this, right? So, here, what we can show is that we have those same positions 1, 2, 3, 4, 5 and 6 and remember that for cis and trans for these alcohol groups to each other that means that on our ring we represent cis and trans as facing up and facing down no matter the position, so we can say at 1 you can show that we can have our OH going up, what that means though is that at 2 it needs to face down, what position is down? it happens to be equatorial once again, okay? So, both of these so far equatorial, the ones on the wedges are going to face up and then the ones on and dashes will face down at whatever position that may be at all of these positions at 1, 2, 3, 4, 5 and 6 carbons. So, for the next one 3, 4 and 5 all need to face the same direction as carbon 1 which is up, so you can say 3 is going to face up here, like this, four you're going to face up and then 5 is going to face up and note that those are all alcohol groups. Now, this one notice it's actually axial, right? Where all the other ones were equatorial, okay? All of these are equatorial, okay? So, finally at 6? Well, as 6 it needs to face down just like carbon 2, so you can show it facing down, okay? So, so far every group is equatorial, right? Except for that one which was axial. Now, what that means is that this is a pretty stable chair conformation because we want our bulky substituents, our biggest groups, to be equatorial and only one is axial. Now, say we did a chair flip, right? Chair flip where we switch all of our groups all the ones that are equatorial become axial? Well, notice is that in this one we had five equatorial and then one axial and our chair flip, what that means is that we're going to get five axial and one equatorial. So, is that good? No, right? this is going to be not stable, so therefore this chair position or this chair conformation that we've drew is going to be the more stable chair, okay? So hopefully this makes sense on how we draw a chair by numbering, showing the position equatorial axial but remembering to indicate cis and trans and how this chair since it has five of its groups equatorial and only one axial, it's going to be a lot more stable than that other chair that we can draw as well. Alright guys, so hopefully this made sense and let me know if you have any questions on this problem.