Organic Chemistry

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18. Reactions of Aromatics:EAS and Beyond

Diazo Replacement Reactions

Aniline reacts with nitrous acid to form a diazo functional group in a reaction called a diazotization. Aryl diazonium salts participate in multiple replacement reactions. We will go over all of these below but first we must learn to prepare a diazo group


Replacement Reactions

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Alright guys and I want to switch gears a little bit and talk about a type of reaction that happens on benzene called a die Azzoni. Um, replacement reaction. So it turns out that Anna Lena remember Nhu on a benzene when it reacts with nitrous acid. So n 02 over hcl you conform a dyas oh functional group in a reaction called a dyas utilization. Okay, now what is the die as a functional group? Because not one that we see a whole lot a die as a group is an end triple bond and group with a positive charge. So it's also called an end to group, right? And to positive. Okay, well, these Dyas oh groups are really good at switching out and reacting with certain types of regents. Okay, so here, first of all, I have a really common pathway to make a dia. So if you start off with benzene, how what's the fastest way to get to a die as a group? Well, right as over this point, we don't have any way to directly add an a lien. So we would just We could just use a nutrition so we could say you could do a nutrition, then you could reduce it using lithium, aluminum hydride or any other reducing agent. You want you guys know which one do I love? The Stannis chloride. So we could also use the status chloride. But really, Let's up to you. You've got your Angeline. And now I do my, um, die as a reaction. I have n a n 02 over hcl that's gonna give you my dyas. Oh, now what's so special about this? Well, once you react and get that dyas Oh, you can do tons of stuff to that day as a group to replace it with another type of compound. So, guys, there's a big list, and I'm just gonna go one by one. Okay, So if you react a die as a compound with see you br you're going to get a promo. Benzene. That's it. If you react a die as a compound with C u c l you're gonna get a chloral benzene If you react to die as a compound with C. U c n. You're going to get what's called a benzene night trial or just a CNN attached to a benzene ring. Okay, don't you wish they were all coppery agents, but they're not gonna be The rest of them get a little bit weird. So iota benzene is formed using K I Okay, now, floral benzene. This one's interesting, guys, because so far you haven't learned how to make floral benzene. I never taught you in E. A s reaction that works with flooring. So if you have an f on a benzene ring, you know the Onley way to put it there, at least in organic chemistry to would be using a die as a replacement reaction. That's gonna be H B F four. Oops, knots Not supposed to be an H f h b F four, you would make floral benzene. Okay, now phenol. There's actually two ways to make it one way. That's awesome. In one way, that kind of sucks the way that's awesome. Which is the older way to make final, which is usually the one that professors are cool with is literally just water. I was trying to use black, so I just put water here. That's great. I mean, that just makes sense. You put water dia so you get a final awesome or I have seen some textbooks that use a much more complicated version of re agents, That is, um see you 20 C u two plus and water. Okay, so that one kind of sucks. So see you 20 C u two plus and water would make phenol. But most professors air fine, which is putting water. Okay. What about benzene? Well, we start off with bending. Why would you wanna make a bending? Well, what if you want to just go back and reverse the reaction? Pretend like there was never a die as a group there. Okay, well, that could be hopeful, because maybe you could use it as a blocking group. Remember, we've talked about blocking groups before, so you could use H three po to H three people to will completely remove the die as a group and just replace it with an H. And then finally, guys, we get couple ing reactions with a zo dies. So let's just back up a little bit. Um let me see if I'm right in the screen. I can't get out of here. But this huge molecule is what we call in a So di. Now, the reason for those two names is pretty simple. A Szot is this group right here? That's an ISO compound. Okay, when you have an n n double bond, the reason I call it a dye is because thes compounds, because they're so highly conjugated, turn really awesome colors. And they're like red colors and orange colors, and they're actually used as very common dies in, like food products and stuff. So these are actually very modern day dies. Okay, now it's called an easel couple ing reaction because these days, oh, groups, I'm sorry. Thes die as a groups will literally couple with another benzene. So it's pretty straightforward. A die as a group will react with another benzene as long as the benzene has an activating group or an electron donating group. Okay, if it has an electron donating group, then it will be reactive enough so that it can react with the die as a group. If you don't have that electron dining room present, it's not gonna work. So as you can see, what winds up happening is that you wind up getting the couple benzene with the old dazzle compound at the bottom. Okay, now we're not gonna worry about any of the mechanisms for these reactions because we're just doing kind of a global view, an oversight, but the most important parts that you memorized these re agents and that you know how to use them in synthesis. Because guess what? Ah, huge part of this area of the textbook is knowing how to make a complicated molecule using both E. A s and dyas or reactions together to make the molecule that you're looking for. Okay, Now, keep in mind, a few of these are unique to die as, oh dia. So is the on leeway to make floral benzene. And it's one of the only ways to make a final. There are some other ways, but you can't use s for that. You have to use some other stuff. And obviously it's the only way that you can make an azo dye. Okay, so keep that in mind and let's go ahead and move onto the next topic