The following molecules were named incorrectly according to IU...

Question

The following molecules were named incorrectly according to IUPAC nomenclature. Give the correct name of these compounds.

(a) 3-oxo-5-methylhexan-2-ol

Accepted Answer

All right. Hi, everyone. So this question says that the given name is wrong based on Iupac rules provide the correct name of the compound below. And here we're given 35 dimethyl or oxo to all. Option A says 24 dimethyl two oxo four hep aldehyde. Option B says four hydroxy 35 dimethyl two hepton. Option C says two hydroxy 35 dimethyl hepton four own and option D says 35 methyl two oxy four hep to do. Now, the most effective way to approach this question is by first drawing it out and we're going to do so using the incorrect Iupac name. Now, when this is the case, right, when I'm trying to draw the structure, given a name, I always start from the right side and I move towards the left because of the right side of the name tells us about the parent chain. So here we have Hepton to all meaning that we're going to have a seven carbon chain with an alcohol functional group on carbon too. So a hydroxy group or oh group is going to be on carbon too. So as I proceed towards the left side of my Iupac name, I'm given more information about substituents. The first one or dash oxo indicates that there is a car bal or ac double bonded to O on position four. And so the phrase 35 dimethyl means that there are two methyl groups, one on carbon three and the other on carbon five. So now we have a structure to work with. So now lets talk a little bit about Iupac naming. Now it's worth pointing out first, what is actually wrong with the Iupac name provider. Now, here we have multiple different functional groups. We have a key to to more specifically the car bono, we have an alcohol as well and we also have methyl substituents on the carbon chain. Now recall that according to the Iupac naming system, certain functional groups are considered of a higher priority than others. The highest priority functional group is always listed as part of the parent chain. So for example, the phrase hap 10 to all implies that the alcohol is the highest priority functional group, meaning all the others are treated as substituents. But that is not actually correct because according to the functional group order, the ketone is of a higher priority than the alcohol. So that is why the Iupac name given is wrong, right. It should be the key to that is part of the parent name. So instead of having the car bal listed as a substituent, the hydroxy group should be listed as a substituent instead. So first, let's start by naming our parent chain. No, the parent chain refers to the longest continuous carbon chain that also contains are functional groups. Now, in this case, the longest carbon chain is still going to be seven carbons long. But recall that the numbering is very important. Now, generally speaking, the highest priority functional group should have the lowest possible position number. But in this case, the car bal is in the very center of the carbon chain. So we could start numbering from either end considering this position here. But regardless, we should ensure that other substituents have the smallest number possible as well. So in this case, I would start numbering my carbons going from left to right, because this ensures that my hydroxy group gets the lowest possible number as well. So now we can go ahead and build our parent name. In this case, we still have Hep to half 10, right? Because our parrot chain is still seven carbons long, sorry Heptane. That's what I meant. But because of the presence of this ketone group, I'm going to modify the name Hept slightly. Now, in this case, because I have a ketone, I'm going to go ahead and drop the E at the end of heptane and replace that with one he turn on. But I also have to be a bit more specific because I have to specify where the car bono actually its and in this case its on carbon four. So in this case, I'm going to place the number four in between the prefix Hep tan and the suffix own though you could place the number four before Hepton know as well. But here we have Hep 10 for on. So at this point, we can go ahead and name the remaining substituents those lower priority functional groups starting off with the alcohol. Now because the alcohol is not the highest priority substituent. It's described as a hydroxy substituent in the actual Iupac name. So we have a hydroxy group attached to carbon two, which means that I would write two dash hydroxy. The position number is written before the name of the substituent and a dash is used to separate numbers from letters. So two dash hydroxy. Now, in this case, we also have two different methyl groups on two different carpets. So in a case like this where you have more than one of the same substituent, a numerical prefix is needed before the name of the substituent itself. So because there's two, in this case, it would be dimethyl, try would be 34 would be tre tetra, excuse me, et cetera. But here we have dye methyl. But as always, we have to list where the metal groups are even if they're on the same carbon, that position number gets repeated twice. But in this case, we have one methyl group on carbon three and the other on carbon five. So that becomes three comma five dash dimethyl, again dashes, separate numbers from letters, but commas separate numbers from each other. So now let's put everything together, substituents are listed in alphabetical order before the name of the parent chain. Now, in this case, numerical prefixes if any are not included in the alphabetical order. So in this case, because the hydroxy, specifically the H in hydroxy goes before the M in methyl, the hydroxy group is written first. And so afterwards, you'd attach the name of the parent chain with no spaces in between. So here I'm placing my methyl substituent after the hydroxy group and then I'm adding my parent name to that. Now I'm also going to add a dash in between hydroxy and the three in 35 dimethyl to make sure my numbers are separated from my letters. So here we have our final correct Iupac name, it's two dash hydroxy dash 3 5 dash dimethyl hep 10-4 dash o and this corresponds with option C in the multiple choice and there you have it. So if you stuck around until the end of this video, thank you so very much for watching. I appreciate it. And I hope you found this helpful.

The following molecules were named incorrectly according to IUPAC nomenclature. Give the correct name of these compounds.
(a) 3-oxo-5-methylhexan-2-ol

Key Concepts

IUPAC Nomenclature

Functional Group Priority

Locants in Nomenclature

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