Give IUPAC names for the following aldehydes and ketones:

Question

b.

Accepted Answer

Hi, everyone. Welcome back. Our next question says, what is the Iupac name for the given ketone? And we have a condensed structural formula that has in parentheses, ch three subscript two CHC double bonded to an OCH two CH three. And our answer choices are a 11 dimethyl butane, two own B four methyl pendine, three own C 44 dimethyl butane 30 or D two methyl pentane throne. So when looking to come up with OPEC name from the structure, skeletal structures are often more useful for this since you kind of get rid of the visual clutter of all the CS and HS the carbons and hydrogens, since they're implied in the skeletal structure, makes it a little easier to focus on the various substituents and functional groups. So let's convert this to a skeletal structure. First, I see I have these two CH three groups attached to a CH which is attached to a carbon group. So I'll start with a line from my ch to my carbon carbon. So there's a line second, carbon has a double bond to an oxygen and then that ch that's attached to the carbon carbon has two methyl groups. So I'll extend my line by one for one methyl group and then draw a line down for a second methyl group. Then con con continuing to the right from that carbon carbon, I have ch, two ch three, so two more carbons in that chain. So I've got my skeletal structure that let me, lets me see that I have two methyl groups. But when I look at this more closely, one of those methyl groups can kind of just extend the chain. And we're looking at a chain that's one carbon longer with a methyl, one methyl substituent. And then we have this carbon group in the middle, which as our, as our problem says, makes this a ketone. So our first step in naming is to find the longest carbon chain, including the kung group, that ketone is our highest priority functional group. So we want it to be included in the main chain. I'll use a highlighting in blue to do that. And as we said, we can extend that chain into one of the methyl groups. It doesn't matter which one, I'll just do the one that's kind of looks like it's the main changes to make it easier, but don't ignore something that looks like it might be a substituent. If it makes the chain longer, you go into that substituent. So 12345. So my longest possible chain including that ketone is a pen ta. So I'll have the root word Penta. And when I look at my answer, choices, I know I can eliminate choice A which is 11 dimethyl butane two own. Since that has the root butane, meaning four carbons and choice C 44 dimethyl butane 30, since that also has that root butane. So you can see in those cases, they wrongly use a four carbon chain with two methyl groups instead of including one of those methyl groups to make the longest possible chain. After this, I need to number the carbons to give the ketone the lowest possible number. But we can see our ketone is right in the middle. So whichever side we start on our kone will be on 123 carbon three, whether we count from left to right or right to left. So we know our, our name here will be Penta and then the ending will be changed to oneo showing it's a ketone. So we'll put PTE and after the N we have hyphen and then a three and then one. Now sometimes you'll see that number for the ketone in front of pentane. So three pone. The format here with the three in the middle is the more recently recommended Iupac convention, but you will sometimes see it written the other way. So just be familiar with both. So we kind of have our base name here, but we need to locate and number any substituents. And here's where we need to think about our numbering. Again, it didn't matter which side we started from in terms of numbering our ketone, but it does matter for our methyl group substituent if we count from left to right. As I've started to show here with red numbers, our methyl group is on carbon too. If I counted from the other direction, which I'll do it with the blue numbers here. 1234, the methyl group is on carbon four. So that gives a higher number. So we know we need the counting the red numbers from left to right. So I'll race my blue numbers here. So my final step is to add that I have a single methyl group on carbon two. So in front, I'll be putting two hyphen methyl Penta three own. Now, I was trying to draw it on the left side. So I actually left a little gap here. There won't be a space in the actual name. So I tried to write that a little closer together, but just be aware when you're kind of putting these names together, it can be tricky to allow space, but there is no space when you put those two, the prefix and the name together. So our name here is choice D two methyl P three on when we look at our other possible answer. Choice. Choice B it has four methyl Penta three own. So again, that would be if we numbered, going the other direction but since that gives that higher substitute number, that's why choice B is wrong. So again, our name Iupac name for the given ketone is Choice D two Methyl Pentane Throne. See you in the next video.

Give IUPAC names for the following aldehydes and ketones:
b.

Key Concepts

IUPAC Nomenclature

Functional Groups

Structural Isomerism

Watch next