Provide the IUPAC name for the following molecules.
(b)...

Question

Provide the IUPAC name for the following molecules.

(b) Structural formula of a molecule with two hydroxyl (OH) groups, indicating its classification as an alcohol.

Accepted Answer

All right. Hi, everyone. So this question is asking us what is the systemic name of the structure below? So when we're talking about the Iupac name of a given structure, recall that there are a few steps that we have to do first, right. The first step is to figure out the parent chain, which refers to the longest continuous chain of carbons present in the molecule. And if I count right, going from, from left to right across the screen here, I'll notice that my longest carbon chain contains eight cars, which if you recall right corresponds to the parent name of octane. But here, right, we also have to go ahead and figure out the route name. Now, the root name is dependent on the functional group with the highest priority in the given molecule, right? And here notice how we have two hydroxy groups in the molecule, which indicates that it's an alcohol, specifically a dial, right? Because we have two hydroxy groups in the same molecule. So to come up with the parent name, right, we're combining the parent chain with the root name. So that becomes octane dial, but we can't just leave it like this, right? Because recall it for every substituent you have in your molecule, you have to name it's position numbers, right? You have to specifically state where they are in the carbon chain. So here, right, given that my hydroxy groups are the highest priority substituent in this molecule, I have to make sure that they have the smallest position numbers possible. So that's why I started to number my parent chain from left to right now here, right. I'm separating my parent name from my root name with my position numbers in between, right? So after octane, I'm running a dash followed by the position numbers of my hydroxy groups which are three and four. And I'm writing a comma in between them and numbers and letters should be separated in Iupac names by a dash, right? So now that I've finished writing my position numbers, I'm writing a dash before I write dial. And now this is going to be my complete parent name, right? It's not just octene, it's octane 34 dial. So now, right, we can go ahead and discuss other lower priority substituent present in the molecule. And when I say substituent, I'm referring to something that is not part of the para chain but is attached to it. And when I do that, when I look for groups that meet that criteria, I'll notice that I have three methyl groups. So I have three methyl groups in this molecule and I have to list them before I get to the name of my parent chain and my root name. So recall that when you have multiple copies of the same substitute in the molecule, you have to use a certain prefix depending on how many you have. Right? If I had only two methyl groups, I would say dimethyl in my aup pane. But here because I have three, the correct prefix is tri. So it's going to be tri methyl and recall that lower priority substituent are listed before the root name, but I'm still not done right because like I said before, all substituent have to have a position number associated to them. So because I have three met groups, I have to have three position numbers before the phrase tri methyl in my Aup pane. Now here, right? My methyl groups or rather, I have one methyl group on carbon four and I have two on carbon seven. So because I have two substituent, two methyl groups on the same carbon, I have to list that carbon twice. So that becomes four comma seven, comma seven dash tri methyl octane dial because remember you should separate your numbers from your letters with a dash in between them, but I'm still not done right. There's one last thing that we have to take into consideration. Notice how for carbons three and four, we have wedge and dash notation which indicates that carbons three and four are stereo centers and therefore we have to determine there's stereo chemistry. So let's go over the rules starting first by determining the stereo chemistry of carbon three specifically. And I'm going to erase the labels of my parent chain just to make sure that it doesn't get too crowded and too confusing. Right. So, carbon three here, it's a stereo center because it has four different substituent associated to it. Now, according or rather depending on how those substitutions are arranged in space, we can determine whether or not carbon three and carbon four for that matter is in the R or the S configuration. So recall that the relative priority of these substituent is determined by their atomic mass, right? So carbon three here is connected to an oxygen, two carbons that have different substitutes each and a hydrogen. So oxygen has the highest atomic mass of all three atoms that I just listed, right. So that's why my hydroxy group is going to have the highest priority. But like I said before, right, we have two carbons bound to number three here, but each of them are bound to different things, right? So we have to kind of break the tie between these two carbons by considering what else they are connected to and what their atomic mass is, right? So the competition right now is in between carbon two of the parent chain and carbon four. Now, carbon two of the parent chain is connected to another carbon when you disregard carbon three here and two hydrogens. But carbon four, on the other hand, is connected to an oxygen with the hydroxy group, another carbon and two carbons actually. So because of that right, carbon four in the parent chain is connected to more atoms that have a higher atomic mass. And therefore, right, it's going to have the second highest priority when it comes to determining my stereo chemistry. And then my other carbon has third priority. And the hydrogen here that's not drawn is going to have the lowest priority because it has the smallest atomic mass. So when I look at my different substituent now that I've ordered them by priority, right, I can kind of circle through them going in a circle, right? Because when the lowest priority, my hydrogen is in the back. When I go from my first to my third highest priority, I realize that I'm going in a circle counterclockwise. And when you're going counterclockwise with your lowest priority in the back, right? That tells you that you're in the S configuration. So carbon three here is going to be in the S configuration. So now let's compare that two, our second stereo center which is carbon four, right, carbon four is bound to three carbons and a hydroxy group. So because oxygen has the highest atomic mass, my hydroxy group is going to have highest priority once again. But let's compare all three of our carbons and see how the tie is going to break. So the first carbon that I'm going to look at is going to be carbon three in the parent chain because notice how it's bound to another carbon oxygen and hydrogen when we disregard its connection to carbon four in the parent chain. Now carbon five in the parent chain is bound to another carbon and two hydrogens. But my methyl group here is only connected to three hydrogens. So because of that, right, my meo group is actually going to be my lowest priority because it's only connected to three other hydrogens. And therefore, right, carbon three in the parent chain is going to have second highest priority and carbon five and my parent chain is going to have the third highest priority. So here notice how my lowest priority substituent is actually in the front. And when I draw a circle going from 1 to 2 to or first to third highest priority, I'm going counterclockwise. But because my, my lowest priority is in the front here, the fact that I'm going counterclockwise indicates that this is the R configuration. So now I can list stereo chemistry and recall that all stereo centers are listed in parentheses following or before the rest of your iupac name. So last but not least, right, I'm going to list my stereo centers in order along with their configuration. So that is three S comma four R close parentheses. And so this is going to be your final answer. Your complete iupac name is three S four R 477 tri methyl octane 34 dial. So if you stuck around to the end, thank you so much for watching and I hope you found this helpful.

Provide the IUPAC name for the following molecules.
(b)

Key Concepts

IUPAC Nomenclature

Functional Groups

Carbon Chain and Branching

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