Epimerization

Hey, guys, in this page, I want to talk about a base catalyzed reaction of mono sack rides, which is called epi memorization. So guys, in basic conditions, it turns out that mono sacha rights can undergo a multitude of todd immunizations and isomerization that make life really complicated. In fact, it's for this reason that we typically don't expose mano Sacha rides to base because it leads to so many by products. Let me show you one of them. So the most straightforward of these is EPA memorization. OK, EPA memorization. Remember what UNEP immer is? It's when you are switching just the position of one Kyle center. Now, when you are switching the Kyrill center of C one that makes animals, and that's called mutual rotation. But when you're switching the position of C two, that's called epi memorization. So mono sack rights will readily ep memorize the sea to position several possible mechanisms exist. This can either proceed through an immolate mechanism or an in denial mechanism. I'm going to show you both of them, but let me just show you kind of the general reaction to start off with. So once again, I'm just kind of picking on our beta d Google. PIRA knows because it's a molecule that you should be really familiar with by now. And I'm showing you what happens in base. Well, we've already discussed mutual rotation. Right? Mutual rotation is essentially EPA memorization off the of C one. Okay, It's where you can get that Looks like C l. It's where you could get carbon one to form to animals to form some of the Alfa and some of the beta. Okay, we've already discussed this, but it turns out that another reaction that could take place is EPA memorization. Where now, B d. I'm sorry, Beta d Google PIRA knows can equilibrium rate into Di mana. Pira knows. Why is that? Because it turns out that now the two position can actually switch from going down to going up. How does that happen? I'm going to show you the mechanisms, but I just want to show you that both of these air gonna happen at the same time and it's uncontrollable. You're going to start to get mixtures of ice swimmers because you're going to get different animals and now you're going to get different animals of a completely different glue of a completely different mono sack, Right? Manos is a different mono sack right than glucose. That's because now the O. H. Is gonna face towards the left instead of towards the right. Also noticed that in the EP immunization, the animals are also in equilibrium with each other. So it's just a big mess. All right, so in the next video, I'm gonna show you the immolate mechanism, and then I'm going to show you the in dialogue mechanism.

So let's go through the immolate mechanism first. And actually, my first question for you is can you think of any reasons why? Specifically, the sea to position of a mono sacha ride is susceptible toe memorization and base. What we're talking about is this position right here. Can you think of any other principles in inorganic chemistry that would make that position specifically susceptible to base? And guys, we do know of Ah, principle that would apply here. And that would be the principle of Alfa carbons. Remember that Alfa Carbons, more than usual, are uniquely acidic due to their proximity to a carbon. Neil, remember that the Alfa Carbon is always gonna have hydrogen. Is that air much, Much more easy to deep protein eight than other hydrogen. While these other hydrogen is have Pekka A's of I don't know, you know, around 50 this guy here is gonna have a peek a of around 20. Specifically, when I say this guy, I'm talking about this hydrogen right here because that's the only Alfa hydrogen. So in the presence of base, it's not gonna be difficult for my for my o h to remove that Hydrogen and Forman evenly, and that's exactly what we're gonna do. So let's go ahead and do that here. The first step is that my O H minus or my base comes in, takes away, and h I make a double bond and a kick electrons up to the O. So what that's gonna do is it's gonna form and an elite that now looks like this double bomb here. Oops, no dove on here and negative charge here. Notice that now I've lost the stereo chemistry of this. Ohh. This o. H is now trigger on a tribunal plane or carbon. It could either be on the right or the left because it's now a double bonded. Now, guys, there may be some of you that air saying, Johnny, that's not how I usually draw immolates. Usually, how I draw Emily would just be with a double bond H and with a negative here Is that also possible? Totally. That's the same thing. These air actually resonant structures of each other, so it's totally fine if you draw it that way. The only reason I drew it this way is because that's the way your book tends to draw it, and that would be like the major contributor of the mainly So your book tends to draw like that. But if you in principle, this is the same exact reaction if you just draw the negative on this carbon because once again, what's gonna happen is that that o. H is gonna be able to flip back and forth because now it doesn't have stereo chemistry. Okay, Does that make sense? Awesome. So now, guys, what happens? Well, now we would just protein it again or not Protein eight again. We would now prote me. So then, in the next step, you have water, okay. And what you're going to do is just reform the double bond. So the double bond, I'm sorry, reform the carbon deal, so this negative charge is gonna come down, make a double bond, and then this double bond is gonna grab H. And now it's going to become the alga hide once again. But notice that because we lost the stereo chemist, the stereo chemical information on that C two carbon. Now it's possible for the O. H. Two basically rasam eyes and go to the other side. And by the way, guys, this is not unique to sugars. One thing that we learned in immolate chemistry is that immolates always rasam eyes the Alfa position. So essentially nothing new is happening here. All we're doing is we're rasam izing the Alfa position of the sugar which happens to be the sea to position. So this totally falls in line with all the principles that we learned about immolate from immolate chemistry from your Alfa Carbon chapter. Okay, awesome guys. So that was the immolate mechanism. And next I want to show you guys the in denial mechanism, which is a competing mechanism that accomplishes the same thing.

Okay, guys. So the in denial mechanism is super super similar. We're gonna go ahead and take away the H, make the double bond kick electrons up to the Oh, this is going to give me a negative charge here and a double bond here. The only difference, guys, is that I'm now gonna protein eight. So I'm gonna protein ate that negative charge to give me literally what's called an dial in Diallo, meaning that I have a double bond with two alcohol's on it in denial. So that's my in denial, Intermediate. Now that and I'll Intermediate once again, the information of C two has been lost in terms of the stereo chemical information. It could go in either direction. So I'm just going to go back to the original easily and back to the model sack. Right. So now in this next step, I'm going to take base again. I'm gonna deep protein eat, and that's going to give me a negative charge here with its old bond. And then finally, I'm going to reform the carbon eel and grab an inch, and that's gonna give me my femur. Where now the O. H. Is faced towards the other side, and I now have a new a new mono sack ride. And basically what what just happened was just another route towards C to F memorization. You might even say Johnny like it seems unnecessary. Why did you add the? It's basically you're just adding a proton to take it away again, and that's exactly it. But this is one of the important mechanisms, one of the other important ways that EP memorization can take place. So just so, you know, basically in denial is just a longer version of Eataly, because in Italy I just kept it as a negative charge and went back here. I protein ated deep, rotated again and then finally went to the primer. Okay, hope that makes sense. The same thing happened at the end. Let's keep moving on.