Hey, guys. So now we're gonna focus on a specific type of ring called on annually. So annual leans or Polly all offends, as they're sometimes called our monos. I click hydrocarbons one ring that air fully conjugated. So that means that to be an annual lean, you need to be on Lee one ring, and you need to have alternating single bonds and double bonds like you would find in benzene. Okay, Now, due to their simple structure, do the fact that you can always predict that it's gonna be a single bond double bond, and it's gonna alternate the names of these annual leans can be simplified to just the number of carbons in the ring and then put it around bracket and then annually. So, actually, if you think about it, a benzene is a type of annually in right. So benzene can also be simplified to the name six annually, which is pretty cool. So if you're just walking around campus and you see someone with a clutch shirt on and has a benzene, you could be like that's a mighty fine six annually in you have there and they're from clutch, so they're gonna know what you're talking about. They're gonna give you a fist bump right in the middle of the student union. You guys are gonna be awesome. So anyway, point being that these annual lines can be summarized by the number of carbons. And as you see, I have two different Anya leans here. I have six annual lean. I have eight annual lean. Now here's the deal. Remember that rule I told you guys about Plain aren t I said you know what? You can pretty much just assume that every molecule is gonna be plainer unless it's drawn really weird. Well, that rule is still gonna apply, except not to annual leans annual leans or the one exception. Why? Because annually ins could get very, very large. Imagine just putting, like, 12 or 14 or 20 in front of the annual in. You're going to get this massive ring. And the thing about large rings is that those bonds get wobbly so they can start to bend. They could start to twist, and they can start to go in directions that will not form a plane or ring. Okay, so this could present a little bit of a problem tow us. We college students that don't really know if something's gonna be playing or not. Okay, we're gonna have to memorize some specific trends to be able to predict if something's gonna be plain or not. Now, just a note of caution here. This is not something that most professors they're gonna ask you to know. Um, nine out of 10 professors are gonna just brush over this subject and say, you know, pretty much assume that it's plain, or unless I tell you the reason being that in order to really tell a molecule is gonna be plainer or not, you have to use X ray crystallography to measure the bond lengths. And that is not something a professor wants to go into during in a college organic chemistry class. All right, so I'm gonna teach you these rules just to be comprehensive, but I want you to keep in mind that you might not have to use this on the test at all. Okay, so here we go. I just want to show you guys the difference between six annually in and eight annual lean six annually, nor benzene is too small to fold or anything. So it's just gonna be plainer. Whereas eight annual lean would normally be What type of domesticity? Anti aromatic, right. This is a This is an anti aromatic molecule if it's drawn plainer, right. But what eight annually in actually does because it hates being anti aromatic, is it folds up on Wikipedia, calls it like a tube shape. I call it like a taco shaped cause. I'm really hungry, and it kind of looks like a taco, and you could put some like mystery meat in there and stuff. And the problem with that, actually, the benefit of that is that these orbital's end up not facing the same direction. And what did I tell you? Guys happens if you're orbital's face, different directions, they can't congregate. And if they can't congregate with each other, you don't have air with anti are authenticity. So that means that eight annual lien actually exists in a non aromatic state. Isn't that crazy? So what are you supposed to do? You're supposed to memorize that this molecule actually does not look like a plane or structure. It looks not. It looks non plainer or non aromatic. Okay, so now what I'm gonna do in the next video isn't gonna teach you exactly what those rules are again. Remember that you may not even need to use this on your exam, But I'm just gonna teach you in case you're curious or in case your professor is really stressing this in class. So let's go on and learn those rules.

I'm gonna teach you guys this rule through really interesting example that might actually come up in your homework. So eight annually is also called cyclo Octa Teacher in or caught for short. That's what I like to call it, at least to call it caught. Cyclo Octa teacher in. Okay. And remember that this is your taco molecule, right? This is the molecule that hates being anti aromatic, so it folds on itself so that it becomes non aromatic. Okay, well, here's the crazy thing. What happens if I ionized it to give it a net charge of two negative? Okay, So what if I add two negative charges to the cyclo off the Tetra in? Well, it turns out well, first of all, what's that called? That would be called in eight annual lean. Die an ion. Okay, because you can see here as too negative charges. What would be the number of pie electrons in this molecule? Now let's count them up. It would be 246 But now wait. Anti encounters to 78 10 rights. We have 10 pile elections. Is that a good number or a bad number? That's Ah Hucles Rule number So this has an aromatic number of electrons. But remember to be aromatic, you need to be plainer. What did we say about the taco? It's not plainer, but wait, Here's the confusing part, guys, because molecules love being aromatic, they're going to do whatever possible to be aromatic. And they're also going to do anything possible to not be anti aromatic. That's the theme of this pattern here. So it turns out that if you have a negative a two negative charge on your molecule, it's actually gonna flatten out again to become plainer. So this molecule actually is aromatic. I know that sucks in terms of memorizing, but you have to think about it maybe less in terms of memorizing and mawr. In terms of motivation, thes molecules are motivated to be aromatic, so they're going to do anything they can. And they're unmotivated to be anti aromatic. So they're going to do anything they can tow fold out of the plane so they don't have to deal with that. Okay, so what are these rules that I keep talking about? Well, here it is. This Onley pertains toe All CIS annually is, by the way, so we'll be in all CIS annually in it just means that all of your double bonds have single bonds that are facing in towards the ring. So both of these would be examples of all CIS. Really? Uh, if you want an example of not Alceste, it would be something like molecule B where molecule d. As you can see, there are some trans bonds here that's a trans, and that's a transplant. So these larger rings would not apply to my rule. And these were just gonna be special cases that I'm gonna tell you about, Okay, But my rule specifically applies to stuff like cycle architecture in or this big thing that I have in molecule A. So let's go ahead and take a look. If you have four end plus two pi electrons, is that a good number or bad number? It's a good number, right? So these molecules are gonna want to do anything possible to be aromatic, Okay? And it turns out if they have nine carbons or less, okay, nine carbons or less. They will become plainer to be aromatics. They will be plainer. Okay. However, if they have 10 carbons arm or and they're all CIS, then they're gonna be too strained to make a plane or structure because those bond angles are gonna wind up getting more and more shallow, so they're not gonna be able to meet the 120 degree bond angle, and it's gonna be too stretched out. So this will be to strained and it will actually become non aromatic. Okay, so it's kind of a sad situation. It wants to be aromatic, but it can't meet the right bond angles. It's just too big to state as a plane, and it's going to start to twist. Okay, so that's if you have foreign plus two. So this is the good numbers, right? Well, what if you have the bad numbers for N, then think about the motivation here. It's trying its hardest toe not be anti aromatic, Right? Is trying to avoid anti air Metis City, so it's going to do whatever it can possible toe fold out of the plane. And that's exactly what happens if you have eight carbons or more. If you have eight carbons or more like cycle Oxitec train a annually in, you're gonna be non aromatic because you're gonna fold okay, just like we did. I'm just gonna put here fold taco, Okay? I'm literally writing talk with her. So you remember. It's gonna fold like a taco on itself. Okay, but what happens if you have seven carbons or less? Well, then you're in a tough situation. It has seven carbons. Or I should say I keep saying carbons, but I just mean Adams seven atoms or less than the ring, then it's too small to fold, so it's gonna have to be anti Iraq. So I'm gonna put here too small. Two fold. And that means it's gonna be anti aromatic. Okay, so that's the rule. Another note here, guys, this is just like a note of guidance here. It turns out that I put together these rules over years of tutoring and year and look, doing a lot of research online and trying to figure out what most professors considered to be anti aromatic, non erratic. But this is actually controversial, so I'm gonna go ahead and right here in a little bracket. I'm gonna put controversial because some professors remember I told you this has to do with bond lengths and x ray crystallography. Maybe your professor is like a professional X ray crystallography, and they have their own idea. Of what? Of some of these molecules. So obviously go with your own professors judgment. If they decide that they want a seven member ID ring to be non aromatic, then go with it. Just go with the flow. But these rules should apply definitely to your textbooks and should apply to most sources that you would find online or most professors what they think. OK, but don't argue with your professor about this one. In general, don't argue with your professor because they're the ones that give you a grade, not me. All right, so for the following molecules, go ahead and use the rules that we talked about to figure out what they would be. Um, as you can see on Lee, compounds A and see actually can use these rules, meaning that B and D I will address separately as different types of molecules. Okay, so go ahead and do a and then, you know, we'll just take these questions one at a time.