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Organic Chemistry

Learn the toughest concepts covered in Organic Chemistry with step-by-step video tutorials and practice problems by world-class tutors.

19. Aldehydes and Ketones:Nucleophilic Addition

Naming Aldehydes

1
concept

Nomenclature

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Hey, guys, let me teach you how to name Alba Heights. So like many other functional groups, Alba hides are gonna be modifying the route name of the carbon chain. So take, for example, alcohol. We know that alcohol's you take out the e and to replace the e of the Al Cane with Suffolk's ol. So then ethane would become ethanol guys. It's the same thing with Alba hides. It's just gonna change one letter. It's gonna be the Suffolk's A L. Now that actually could be a little confusing, because those Suffolk's sound really similar. So ethanol would be an alcohol. Ethanol would be a two carbon Aldo hide. All right, so you have to be careful about how you say those vowels because they are pretty similar to each other. Now it turns out that there is one major difference between Alba Hides and other functional groups, and it has to do with the definition of what an alcohol is. If you think about it. Alga hides are, by definition, terminal carbon eels. They're always at the end of the chain. So what that means is that we don't need to number them the same way. Would number other functional groups. In fact, it does not receive a location. So you would never say that something is a one. Ethanol. Why? Because the carbon Neil has an H on it. Remember, Aldo hides have an H on them, so that means it's by definition on the end of the chain, so you don't need to name the location. So instead of saying one heck, Sanel, you just say hexagonal because there's no possibility of having two or three Hexen out. Why, if it was a two or three now would be inside of the chain, and that's called the key tone. So it becomes a different functional group of its internal. But if it's terminal, then it's an alga hide, and we don't need to name the location. We just assume it's at one of the ends. Okay, now there are gonna be sometimes where you're not able to put the alga hide inside of the route and it has to stick off. Ah, good example of this is ring, So we're gonna do a name. Name example in a second. Whereas you notice the alga height is not part of the route chain because the root chain is gonna be this five member bring. Well, when that happens, then Alba hide gets a special name because it's a substitue int. So as a substitue int, it receives the name car Valda hide. And it does. It's not does. And it does receive a location. Okay, so if you're able to put it into the root chain, then the route is gonna be al. There's gonna be no location because you assume it's at one of the ends. However, if you're not able to put the carbon Neil the alcohol in your route chain, let's say that it's a substitute. It's a branch off of that route chain. Then you do have to give it a location because I need to know where on that chain is it. And you have to call it a car. Valda hide instead of an alga hide to indicate that is now it is now a substitution. Okay, so if you're a little bit lost, don't worry about it. We're gonna do two examples, and by the end of these two examples, you're gonna have a pretty good idea of what's going on. So go ahead and try the first one. Name it, you know, according to the rules that I told you, and then I'll give you the answer
2
example

Name the aldehyde

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All right. So the first thing we would do is we would start off with just the al que nomenclature rules which say that you have to find the longest carbon chain. And ideally, we want the functional group to be on that chain. So I'm gonna pick thes six carbons. Okay, so that would be 123456 This would typically be a heck sane, but I'm going to switch out that e ending for Hexen. L okay. Also noticed that my alcohol is part of that change. So, um, I gonna number it as a one. Hickson Al No, Guys, I'm just gonna leave it as hexen now, because I'm assuming that it's at one of the end of the chain because it's an AL died. Now, we're not done. We have a substitue int. And that's just gonna be, you know, we get it. We would definitely give our first carbon name Or number two the Alva High. That's gonna get priority. It's a modifier. So it gets priority, and then we go from there. So it would be a five metal hex enough. Okay, once again, just toe prove my point A little bit more guys. The reason that I don't have to put five month of one Hexen AL is because this is the only place it could be. It's either gonna be here or it's gonna be here because it has an H on it. If I were to, let's say, Put the carbon Neil in the middle like this, that's not now to hide anymore. It's a key tone key tones. You have to name the location, but Alba high detail, cool guys. So that's that one move onto the next.
3
example

Name the aldehyde

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Hey, guys, this video is actually a re record because the first time that I recorded this video, I actually got the name wrong, which shows that this must be a pretty tricky molecule because I'm a tutor and I even got the name wrong. And the reason it's more confusing. The normal is because this is a cyclic Aldo hide and cyclic Alba hides get their own Siris of rules. So I'm gonna list them out here. It's three bullet points that I want to write out for you. So the first thing is that when you have a cyclic Aldo hide, let's just write this down. Oops, not a when you have a cyclic Aldo hide number one, it gets named as a car. Valda, hide. Okay, So what I mean is that every time you have a alga hide that sticking off of a ring, that substitution is actually gonna get called a car. Valda height. Not just analogy, hide. Okay, that brings us to the second point. The second bullet is that it's named as a substitue int. And what do I mean by that? What I mean is that it's not a modifier, it's not going to show up in the root of the change of the AIPAC name. It's going to show up in the front where the substitue INTs go at the at the beginning of the name where the substitutes go and the last one. Oops. The last point. Oh, God. Okay, there we go. The last point is that it gets priority over other functional groups in terms of numbering. Okay, So, like, for example, it beats double bonds. Okay, So what that means is that I know that this molecule is going to be numbering numbered, starting from the one position here, which means that this is gonna be the too, because I would go around in the in the direction of the next highest priority functional group, which is a double bond. Okay, great. So now we just have to put this name together. We know that the route just let's just do it in stages like we always do. The route is going to be a two cyclo repenting. Now, why am I saying that? Well, pent, cyclo pentagon would be the normal route, but there's a double bonds starting at the two positions, so I'm gonna call it to cyclo Pantene. What about the substitutes? Well, I know that there is just simply a one car. Val died. Okay, but if there had been others and sorry. You can see that now. If there had been other substitutes, then you would list them out here. So now we just have to put the entire name together and the entire name together is just gonna be one karbala to hide to cyclo pending. Cool. That's it. So notice that it's very different from the rules for typical Alba hides. But it's not that hard. It gets named as a car. Valda hide its name substitute, meaning that it's going to go in this part of the name at the beginning, and it always gets priority over other functional groups. All right, so that's it for this video. Um, let's move on to the next one.
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