Non-Carbon Chiral Centers

Alright, guys, in this video, I kind of wanna have the final word on Chire ality because it turns out that there's one assumption we've been making that isn't totally correct, which is that a Cairo center is always gonna be a carbon. It turns out, guys that there is a such thing as non carbon Cairo centers and that's what we're gonna focus this page on. So Kyra ality can exist on Adam's other than carbon. Technically, any atom that's capable of forming four different bonds to four different types of atoms could be a Kyle center. Now, carbon is definitely the most common situation, and you could probably get through all of or go just looking at carbon. But some professors, some textbooks, may try toe quiz you a little bit harder on these other atoms that can also form for bonds and become Cairo. Okay, so what are these atoms? Well, silicon silicon is right under carbon, right? So silicon is like a no brainer. That could definitely be Kyra well, but also nitrogen, which in some cases makes four bonds phosphorus, which in some cases makes four bonds and sulfur, which in some cases makes four bonds. Okay, so thes air, all atoms that we want to potentially be looking at as Carl centers, but again, rarely. But it can happen. Okay, Now, I have all these different types of carl centers drawn out for you. But one of these is not Cairo. And the one that's not Cairo is any neutral nitrogen with a lone pair. Now, I just told you guys that nitrogen can be Kyrillos, So why am I saying that? Well, let's look at what a mean looks like when it has a lone pair. Well, you've got the nitrogen. You've got your three groups for sure. 123 Now, does your loan pair account as 1/4 group? That's basically the question is the lone pair of fourth group. Well, it turns out that for a neutral mean, the answer is no. And the reason is because for its account as 1/4 group, it should stay in one place if it moves. If it starts switching places, it can't be 1/4 group and a means have this amazing ability to do something called a mean inversion. What a mean inversion means is that the lone pair isn't always stuck to the top. It can also flipped the bottom. So that means that this isn't gonna be a Cairo molecule because I never know exactly where that loan Paris it could be at the top. It could be at the bottom. The way I like to think of it is it's almost like an umbrella. Right? So imagine that I'm holding this umbrella above my head, and I've got the are groups facing down, And then after it inverts, my umbrella goes up and I break my umbrella. So this is like the bottom one is kind of like your broken umbrella situation. Okay, well, a meaning version is very easy to do because it has very low energy. Okay, 24 kg per mole is all you need to invert that lone pair, which in most cases, in ambient temperature there's plenty of energy around to do that. So it turns out that a typical mean is not Cairo. So don't freak out. You're pretty much never gonna have a Cairo mean, so don't worry too much about that, but sulfur is in a similar situation. Notice that like a cellphone IAM cellphone, iam salt. Okay, this would be a sulfur that has a positive charge because it's missing some electrons. But notice that if you put Sulfur in the same position where it's got those three groups and it's got a lone pair, the energy for that lone pair to invert is much, much higher, its way higher. So in room temperature, this is not going to invert. So that means that this is Cairo because you've got your Group one Group two, Group three and I know that my lone pair is going to stay stuck right there. Why? Because I don't have enough energy in the environment to invert that lone pair. Okay, now, if you're really interested in thermal dynamics and stuff, there is a temperature at which this loses its Chire ality, right? If you increase the temperature enough, then the ambient energy will be sufficient to make that lone parent vert. But again, that's a very, very high temperature. So in most conditions, this is a Cairo molecule. Now let's look into the other one's really quick. So what kind of a mean, or what kind of nitrogen is Tyrell A Quaternary? You mean? So that means any nitrogen that has four bonds. Two different things. So in this case, 1234 That definitely could be Kyrill again. It's only gonna happy with the nitrogen with a plus charge, because any time that nitrogen has four bonds, it has a plus. It's not be right. So also self oxide. So sulfur that has, uh, it's called a self oxide. There's a functional group where you have to our groups. You have a dull Bonta. Oh, and you have a lone pair. This can be Kyrillos Well, because it's difficult to invert. 123 and then this council's group for Foss fiends so in or go to, we're going to deal with some Foss fiends. And what you're going to see is that 123 These are Cairo because Foss fiends are much more difficult to invert than nitrogen. So Foss fiends kind of like our cell phone IAM salt. This is gonna have a very high energy of inversion, so this is going to stay exactly the way it is. And then, finally, the no brainer. Silicon Silicon is an analog of carbon, meaning that it's an atom that behaves very similar to carbon. So this would be a Carbon Carol center. If it was a carbon, it's also a carol center if it's a silicon, so I'm gonna go ahead and check that off making sense awesome.

this might be complete overkill, but I'm just adding this just to be comprehensive. What if your professor were to ask for the R and s naming off a non carbon Carl center? Well, it turns out that it's very easy to do. That's what I'm teaching you. There's just one extra rule you're going to use the same RNs naming that we use before. But the extra rule is that the lone pair, she is always group number four. So, whereas with our other molecules, if we saw hydrogen, we always assumed Okay, that's the last priority group. That's group number four. Now, there's something even worse than hydrogen. And that is a lone pair because a lone parent doesn't even have an Adam in it, right, It's just electrons. Okay, so we're gonna I'm gonna show you guys. How did Ur ness with a phosgene? But I do have to make one correction. Go ahead and take this Ethel group and change it toe. Ah, hydrogen. So for all of these, change it toe Ah, hydrogen. The reason being that there's a typo here, I for some reason I put metal is too. And Ethel is three. Should have been the other way around. So I'm just going to change it to hydrogen, and then that will actually be the third group. So let's do that everywhere. Cool. So notice that you would use your prioritization just like before, according to atomic according to atomic number. Right? And, um, what I have here is fennel versus metal versus hydrogen. Fennel is gonna beat metal. Metal is gonna be hydrogen, but hydrogen actually beats the lone pair. Okay. Now, according to our Arness rules, remember that your fourth group always has to beware on the dash. Right. So we're gonna swap. We're gonna take one, which is on the dash. We're gonna take four, and we're going to swap those numbers, right? So that means that what it becomes is that now the four is in the back, so I don't care about it anymore. And now I just go ahead and I do my rotation. So this is not my new one. My new to my three. I go around that looks like what direction it looks like. An s right. So I'm gonna write s here. But since I had to swap, that means I'm also going to swap signs at the end, meaning that this is actually in our Cairo center and I'm done. Alright. Cool guys. So now you guys were just experts on all carol centers. They don't even have to be carbon. You even know how to do sulfur, silicon, phosphorus and nitrogen. Awesome. So let's move on to the next video.