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Amine naming 2

Amine naming 2. Created by Sal Khan.

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Video transcript

Let's see if we can handle some slightly more difficult amine naming examples. So if we look at this blue molecule right here, we always want to start off by finding the longest carbon chain. It looks like it's this chain at the bottom where we have one, two, three, four, five, six, seven, eight carbons. So it's going to be octan. We don't want to just call it octane because we have these functional groups up here, and maybe one of them's going to take higher priority than just the fact that this is an alkane. And, in fact, one of them will. So let's look at them. So over here we an amino group. That would make this molecule an amine. So this is an amino group right here. Then we have this benzene ring. And when benzene is a functional group, we call it a phenyl group. And that's derived from I think it's either the Greek or the Latin word for light because benzene was first isolated from, I guess, the air around lanterns or something, so this is called a phenyl group. And then finally we have this OH, which would make this whole thing an alcohol, or we could call that a hydroxy group, so this right here is a hydroxy group. Now, this is just something that you need to know. There's no way to kind of deduce it. The people who've decided how to name things just decided that certain groups take higher priority over others. And out of these three groups, the hydroxy group, the thing that's making this whole thing an alcohol, takes the highest priority, so this is what's going to define the suffix. So if we start numbering, we want to start numbering this chain closest to the highest priority group. So we'll start numbering at this end. So it's one, two, three, four, five, six, seven, eight. So we have a hydroxy group on the three carbon, so this is octan-3-ol. If this was not a high priority, we would put a hydroxy in the front, but since this is the highest prioritiy, its defining this as an alcohol, octanol. But we put the 3 there to say it's on the three carbon. And then, of course, this would be 5-phenyl. This right here is 5-phenyl. And this right here is 8-amino. And amino comes before phenyl in alphabetical order, so this whole molecule is going to be-- let me write it over here-- it's going to be 8-amino-5-phenyl-octan-3-ol. And we're done. So this is an aromatic compound because of the benzene ring. It's an amine because of the amino group. And it's an alcohol because of the hydroxy group. Now let's look at this molecule here in green. And actually, I forgot to draw part of it. This is supposed to be a benzene ring. So let me make clear. That is a benzene ring. So let's think about the different functional groups here. And we'll start with the one that you've probably never seen before. This is a nitro group, and it's highly explosive. Maybe in a future video, I'll show you some nitroglycerin and some TNT, as you know, which are highly explosive, but they have nitro groups on them. So this right here is a nitro group. It takes very low precedence in the whole scheme of things. So this will never be the cause of naming the suffix. We just know that this is a nitro group right here. We, of course, have a bromo group that we've seen many times. That is a bromo group. And then we have an amino group right here. So this is going to be-- let me do this in a different color. This is definitely an amine. This is an amino group right there. And out of these three groups, the amino group is definitely of the highest priority. So you might be tempted to name this 1-amino-2,3-brom o-4-nitrobenzene, but when a benzene ring is attached to an amino group, this one also has one of those special names. And let me just do it on the side right here. So if I just have a benzene ring attached to an amino group, so that's an NH2 right there, we call this molecule right here, and this is just the common name for it and it's something to put in your toolkit, this is aniline. So that will be the base name. This whole thing right here we call aniline. Let me write it over here. So this is aniline. And then we always want to start numbering at the group that's really defining the molecules, so we start numbering here. And you want to go in the order where you're going to bump into something first. So, one, two, three, four. So this is going to be-- if we look at them, and bromo comes alphabetically before nitro, so it's going to be 3-bromo-4-nitroaniline. And we are done!