Organic Chemistry

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

17. Aromaticity

Naming Benzene Rings



Benzene Nomenclature

Play a video:
Was this helpful?
benzene is by far the most common aromatic molecule that we're gonna be using this semester. So we're gonna have to get really good at the naming of it. And it turns out that since this is a really old molecule, it's gonna have some distinct and weird name ings that most molecules wouldn't have. Let's just jump right into it. Benzene was one of the first organic molecules to be identified way back in the early 18 hundreds. So we find is that when we're naming these guys common names predominant Okay, meaning that there's AIPAC and there's common. And a lot of common names are based on just weird Greek roots, Latin roots people's girlfriends naming them after like their wives and stuff. It's weird, so most of these names are gonna make sense, thankfully. But there are gonna be some weird names that you don't have a really great way to understand where those names come from. So first of all, we have to know what the bending derivatives are. Okay, now, just so you guys know, your professor may not think that all of these derivatives are important, So you're just gonna have to calibrate this knowledge to whatever you learn in class. I'll go ahead and tell you all the names and then I'll tell you which ones are the most important for you to know. So definitely an alcoholic. Textural benzene gets the name Fennel huge, very important. A method attached to a benzene gets the name tall. You mean an amino group attached to a benzene ring? Gets the name Anna Lean A carb oxalic acid attached to a benzene ring. Gets the name Ben's OIC acid. Okay, this is actually calling me meth Oxy Group. Back when we talked about ethers, we learned that ethers can be named within Alcock. See substitue INTs. This would be like an ether, right? R o r meth Oxy, if you see meth Oxy, that's called on an asshole. Okay, Like I said, some of these you're getting weird. If you see two methyl groups, okay, that's not Tali Lien anymore. So would be wrong to call this metal Halloween. Instead, we would call this xylene. See, I told you they're weird. Okay, What else? Well, if you haven't alga hide on your benzene, that's gonna be called Ben's. I was a hide that would make sense. It's kind of like carb. Oxalic acid is Ben's OIC acid. Ah, benzene, Al Qaeda's Ben's alga hide that one was pretty easy. Now what if you have the most basic key tone? Ehm ethyl ketone. We just talked about Ben's alga hide being the most simple alga Hide or not, the most simple, but Alba hide so metal key tone on a benzene ring is actually a weird name. It's a seat ofa known aceto fen on. Okay, And then finally, um, if you have to alcohol's that air specifically in a one to position next to each other, we're going to talk more about what? Those positions. Actually, you know what we call them and benzene. But if you have those alcohol's right next to each other, that's called a cattle call. Okay, so now that we've gone through all these crazy names, um, I'll go ahead and say that they're all pretty important, except for maybe the ones that I wouldn't necessarily memorized unless you're professor, Really? You know, mentioned them in class is an asshole, so I'm just gonna take this one kind of off the list. Don't worry about it too much. Also, cattle call. I would probably take that off the list. Cata coals become really important later in your medical studies. When you talk about talk about Cata cola means which are neural transmitters and you know their molecules that work in your body. But for right now, just know that this is called a cata. Cool. It's not something you I need you to memorize at this moment. All these other ones, You're going to see it some point this semester for sure. So I would definitely memorized them. Okay, let's not talk about locations. Okay? So it turns out that the way that you number your substitue INTs actually depends on the number of substitutes you have. So mono substituted benzene. No location necessary. So if you have a method benzene, you should just call that tall. You in? You should not call that one Halloween. You don't need to do that. Or let's say you have a chlorine on the benzene. You should not call that one chloral Benzie. And you should just name it chloral Benzie. And so I'm just gonna write an example here of C l. And that would be chloral bending. Okay, Now, guys, I wasn't planning on discussing this right here. But this is this is a better time than you know than any to say. Why the heck that I just put a circle inside of that molecule? I have not done that yet this semester, But just remember that benzene rings don't always have to be written with three double bonds. You could just write a circle. And that means that those double ones, Aaron resonance with each other, which we learned is actually the definition part of the definition of air. Metis city had to do with fully conjugated. So if you get an aromatic molecule in the future, you could just write a circle in it. If you wanna be lazy like me. All right. What if you have so notice There's no location there? What if you have a di substituted benzene? Like I just noticed. I just mentioned 12 hydroxyl groups. Okay, well, in that case, we don't use numbers. If you only have to. We're gonna use numerical. I'm sorry. We're gonna use letter locations. Okay, So, 12 instead of being called 12 we actually call that Ortho. Oh, okay. Instead of 13 we're gonna use the word meta. And instead of 14 we're gonna use the word pere. Okay, Now, these even gets shorter acronym. So instead of Ortho, we would say, Oh, meadowood b m peril would be p. Okay, Now, these words, they don't all make tons of sense. But pere definitely means across from so that helps across from okay. Meadow means middle. Okay? It's something in the middle. Ortho doesn't technically mean next to it. Didn't mean that before, But these days, we'll say that's what the definition is next to. Okay, so Ortho will be next to each other. Peril would be across from each other, and meta would be in the middle. Okay, And those would be the numbers that would correlate to them. Okay, So this is the way that you name a Di substituted benzene, But what happens? Guys, if you're benzine has three substitue INTs on it. You can't use Ortho meta pair anymore because it's gonna be very confusing. Is it? Are you talking about that the first two groups or metal to each other or the first and the third group are are made into each other? It doesn't make sense the system breaks down if you have more than two. So that's we call multi substitute bending. That would be three or more substitue INTs. If you have three or more, then numerical locations are necessary. You can't use Ortho meta pere if you use it. Part of my friends. You look like a dumb ass because you look like you don't understand what oh MMP mean. Okay, so if I were to just let's take a really easy example throw three of the same Adam on it. Okay, so let's say that I were to throw just, um, something. Have a name, get three ethel groups, right. Well, then you would name them literally 1 to 4. Try ethyl benzine. You would not try to use Ortho or Metta or parent in that name, because it's gonna be very confusing. Okay, so that said, we're gonna do some practice. We're gonna put all this together. So go ahead and try to do this first problem naming it according to what we just learned. And then I'll walk you through the answer

Name the following benzene derivative


Name the following benzene derivative


Name the following benzene derivative