Organic Chemistry

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

24. Carbohydrates

Monosaccharides - Osazones

Aldose aldehydes are susceptible to the same nucleophilic addition reactions that we learned in carbonyl chemistry. In this video, we will specifically be looking at amines and what they can form when reacting with monosaccharides. 



Play a video:
Was this helpful?
What's up in this video? We're gonna talk about a carbon deal site reaction of mono sack rides called osa zones. So, guys, one of the reasons that you gotta love mono sack rides is because they have so many functional groups. They have so many alcohol's, they have carbon meals. And in this video, we're gonna talk about a specific reaction that happens to the carbon meal of Amano Sacha ride. And it turns out that al dose Aldo hides so the alga hides at the top of an AL dose are susceptible to the same exact nuclear feel like addition reactions that we learned back for carbon chemistry. Okay, so you can't forget those reactions. Those reactions air very relevant to mono sack rides because mono sack rides have caramba carbon eels that can react in those reactions. So, do you guys remember what would happen when you expose a key tone or alga hide to a primary amine in acid? Do you guys remember what happened? What you would get is an Emmy. You would get a function group called in a mean that had a double bond end to the carbon. Okay, we'll remember that Similarly, if you exposed a carbon ableto a primary amine derivative, meaning it's not exactly ammonia. It's not exactly a primary mean. Maybe it has some Z group or ex group on it, like alcohol or a or a benzene ring or something like that, that that benzene ring would stick off of the end, but you would still get a means. That product would be called a mean derivative. And guys, if you're getting a little bit lost by what I'm saying, maybe you just started clutch and you just started watching this chapter. I have, ah, whole section in Carbondale chemistry talking about Indians, and I mean derivatives. Okay, so you can go back and watch all those videos anyway. What I'm trying to do is remind you of what we already know that we can move on and understand. Osa zones. So when the specific, um, meet primary and mean derivative fennel hydrazine is used, the product is referred to as a federal hydra zone. And these air again, things we've already discussed from the carbon chemistry chapter. So when I talk about final hydrazine, what I'm talking about is this molecule right here. Now this is called a primary amine derivative. Why? Because notice I have a primary. I mean, here, this is a nitrogen with two h is and one our group technically, but that the reason that it's not a mean and it's a it's a mean derivative is because instead of using an our group, I'm actually using what I call my videos as a Z group. Okay. Which is basically something Electra negative or something that is different from our. So in this case, federal hydrazine is a primary. I mean derivative, because it has the N h two and the benzene ring as a Z group. Okay, But you could actually, if you wanted to just write the general formula of this, it would be NH two z was something on the side that is attached to the end. Quote. Well, guys, what we learned and this is this is all right. Now, this is just recollection. I'm teaching you anything new If you're to react a, um primary amine derivative with the carbon eel and acid. What you're supposed to get is that end double bonded to the carbon with the Z coming off. So guys don't actually write this whole thing out. Just let me write it and then I'm gonna erase and show you. So what we would expect according to our rules of using an Indian derivative, is we should expect a double bond end with a Z. Okay? And you might be saying, Well, Johnny, what happened to the H is that's part of the whole mechanism in the mechanism. They come off. But what you get is this group here, and that's called in Imean. Now, the reason that I'm saying it's an Indian derivative because there's a Z group Well, what is the Z group? It's the end of the benzene ring, so it's go ahead and plug that in. And this is what I want you guys to break down. I want us to write down that you would expect to get a double one and with another end with the benzene room and this end the red and does require an H two completed three necessary bonds. So I'm just gonna put H double bond, double bond, double bond. And there you have it. This is what we would expect just even if I hadn't taught you anything new, if you had just seen this re agent with acid in a carbon. Neil, you should know from Carbonneau chemistry that the Alba hide would make a federal hydra zone or a federal hydra zone derivative. Because in this case, um, it's not just a federal hydra zone has a sugar attached to it. That's why I'm calling it a federal hydra zone derivative. Okay, so, guys, so this is the part that you should already know. And that's why I keep saying remember, recall, because it's something that we've already learned from before. But now this is where things get weird because surprisingly when exposed to additional equivalence of federal hydrazine meaning that instead of just using a 11 tau one mole ratio, what if we use three moles or excess moles of federal hydrazine? You're Indian derivative or basically, this thing right here. The federal hydra zone derivative is going to continue to Tottenham arise and react, and the resulting product is going to be something utterly new, completely new that you've never learned before. And that's why we need to learn it here. And that is gonna be ah c one C two die fennel hydro zone derivative that we call in Osa Zone. Okay, so I know that was really big term C one C two die Final hydro zone. But I think that the name there speaks for itself. This is C one, this is C two and basically what ends up happening is that through a mechanism that we're not gonna go through here. We're not going to go through the whole mechanism. It's actually, if you're Professor makes you draw the entire mechanism for drawing an ozone product. Your professor hates you, so I'm gonna go ahead and skip that mechanism here. If you really need to learn that whole mechanism, I'm sure you can find it somewhere on, like Wikipedia or something. But what I really want us to know, it's just the general product, the general idea of this and hopefully really praying for you guys that you do not have to draw this whole mechanism because it's very intense. But what ends up happening is that, um, Todd memorization occurs at this. Oh, so, like, kind of like the double bond ends up moving over here at some point. And then what ends up happening is that tomb or equivalents off your federal hydrazine are going to react at this position. And according to what I'm stating, that the product is that means that we should draw another Imean derivative or another federal hydra zone at the two position. So let's go ahead and do that. Now, what our final product is gonna look like is n with another double bond with another NH and with another benzene ring. Cool. And that is your final product. That is an OSA zone. So a few takeaways here. First note that you always have to use it least three equivalents of the federal hydrazine to produce this. And even though you use three equivalents, you're only going to get to federal hydra zones in your product. So it's kind of just something to keep in mind. Another thing that I want to say that you guys should all be aware of is that usually in a question ah, professor is always gonna want you to go all the way to the oh so awesome. The only reason that I split this page up into Step one for the first one and Step two for the second one was for teaching purposes Onley because I want you to recollect what we already learned. But your professor is never gonna ask you to just draw the first federal Hydra Zone product. Okay? What? They want to see if they if your professor or your textbook or your online homework ever reacts a sack, A ride with the fennel, hydrazine and acid. They expect you to go all the way to the ozone and they expect you. You can skip the middle step. You can just draw the ozone because that's exactly what they're looking for. They're always gonna assume that you have enough fennel hydrazine present to make the ozone. Does that make sense? Cool. So don't don't get too carried away saying, but how Maney equivalents are there. Are there one or two? Don't worry about that. I just did that for teaching purposes. You can understand the reaction better, But really, in actuality, you're always gonna have enough federal hydrazine to complete Theo Schism. Okay, Lastly, I just want to give you a historical point of why this reaction is important and why a lot of professors and textbooks care to teach it. This was a very important reaction for email. Fisher, who's really the father of carbohydrate chemistry. In 18 88 he used osa zones to prove that Glucose and manos were members of each other. And basically, Osa zones were actually very toxic. He ended up dying because he was exposed to so much federal hydrazine and host zones in his experiments that he got, I think, like cancer all over his body. It's a really sad story. Um, it doesn't end there. It gets even more sad. But just letting you know that he's heralded is one of the best chemists ever. And he was the father of sugar chemistry because he was able to use osa zones which crystallize out of solution very easily to determine that that two different types of sugars were ep immerse of each other. And then eventually he was able to build this entire beautiful proof called the Fisher proof that showed what all of the structures of mono sack rights were. So what I'm trying to say is that we don't really use Osa zones that much now, But the reason that they continue to be taught in textbooks is because they were very important back in the day to prove what the structure of mono sack rights was before we knew what they looked like. Awesome guys. So hopefully this made sense. Let's go ahead and move on to the next video.