10. Addition Reactions
Halogenation is one of the most popular addition reactions and is the primary method for making vicinal dihalides.
General properties of halogenation.
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Now we're gonna talk about one of the most common addition reactions in this entire section and that's called Halogen Nation. So just get right into it. So halogen nation is the process of taking a double bond and adding a diatonic halogen. And at the end, what we're going to get is anti die. Hey, lights, anti visceral die! Hey, lines. All right, so let's go ahead and just talk about the general features of this reaction. First of all, the mechanism is gonna have an intermediate, and that intermediate is gonna be similar to other ones. We've learned it's gonna be a bridged I on. Okay, so maybe you can already start to visualize what you think. That might be sorry about that. Okay, the stereo chemistry is gonna be anti okay. As I just showed you guys, you're gonna get anti die. I mean, anti die. Hey, Allied's so it would be anti. And then my product is gonna be like I said, visceral die. Hey, Allied's okay. Now, just to remind you guys, the word vis inal is a word to me that there's two things next to each other. Okay, so this would be this relationship here would be visible because they're right next to each other. Vision was also the same as saying one to basically, you have something on the one position and something that the two position and I'll be visible. Okay, so will there be rearrangements in this mechanism? No, there won't be because there's no carbon cat iron. And then finally, since I'm adding two of the same thing, I'm not gonna worry about Markov Nick off because I'm adding two of the same thing, so it doesn't matter, so it's just scratch that out. Okay, So as you guys can see, the reaction looks pretty simple. We've got a double bond, so he notices addition, we've got an electric follower, adding, Now, notice that I have CCL four down here. If you guys remember, this is actually gonna be a a polar solve it, okay. And a polar solvents are inert. That's not going to do anything, so don't even worry about it. That's just something that it happens to help the reaction, but it's not gonna do anything. Alright. Another common solvent that you might see is like ch two c. I'm sorry. Ch two c l two okay. That just means it's the same thing. It just means instead of having to four chlorine, you have to chlorine from two ages. Regardless, thes air. Just solvents that don't do anything. Okay. At the end we get Is those visceral die? Hey, Allied's let's go ahead and look at the reaction.
Opening of 3-membered intermediates/molecules always results in anti-addition.
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So the mechanism works like this. Basically, you've got a double bond, and that double bond is nuclear. Philip, it's looking for something to give its electrons to. And I know that halogen seem to have a lot of electrons, but they're also very what's called polarize Herbal. So what that means is that electrons wind up moving a lot and wind up causing imbalances in the electron cloud. So at some point, there's gonna be a part of the X or part of the halogen. That's not gonna have too many electrons, and the double bond is gonna pounce on that. So what's gonna happen is that the dull pond is gonna grab one of the X is now the X doesn't like tohave that many bonds. So it's gonna go ahead and break upon if you make a bond of to break upon, but similar to other bridged ions that we've looked at before. If we make that bond, then we have toe make another bond back to the double bond. What that's going to show is it's gonna make a bridge instead of just a single bond to one side. Okay, so those are three arrows. We're gonna wind up getting is a bridge, ion. In this case, this is called a polonium ion because instead of, you know, basically have instead of a Carvel Catalan, I have a three member ring, and one of those atoms is a halogen. Okay. For example, if this was a Romanian, I would call it a bro. Monium Ion. All right, Now, this positive charge is going to be distributed throughout all three of those atoms, So I'm gonna have a partial positive here. I'm gonna have a partial positive here. Partial positive there. Okay, but one of these atoms is gonna have the most positive density. Can you guys guess which one? It's gonna be the atom that is the best, that stabilizing positive charges. And that one's going to be the most substituted side. So if they both had the same substitution, then this xnegative could really attack anywhere. But since in this case, one of them is tertiary and one of them is secondary. What that means is that I'm gonna go for the more substituted one. So my xnegative is gonna basically do what we call a backside attack and s and two reaction if you haven't learned that yet. That's okay, but just, you know, the backside attack. And then if we make that bond, we're gonna break a bond. So then we would break the bond to the X, just like any reaction that involves a three member ring. Any time that we break it open from the base, we're gonna have to make anti products because there's a lot of potential energy in that three remembered ring. And once you break it, it's gonna snap open, and they're gonna face opposite directions. So what that means is that if my ex negative attacks from the top, my ex on the ring is going to go towards the bottom, so it's gonna cause anti products. So over here, what I would get from my final product is I would get Let's let's say that the X had attacked from the top. Then that means that this metal group would face towards the bottom. And that means that this method, I mean, that means that this X would face towards the bottom. So what I'm gonna get is an anti product. Okay, Now notice that. Do I have any Cairo centers here? I actually do I have to. Carl Centers. So what that means is that I'm also going to get the an anti mur and the Anant humor would just be if it had attacked from the bottom, Then I would get this exit, the bottom, this metal group at the top, and then this X at the top. Oops. Oh, my God. This program could be a little dumb sometimes. Sorry about that, guys. I'm really struggling here. There we go. Okay. So those are two an anti MERS. These would be produced in even amounts, so that would be receiving. Makes sense. Cool. So this mechanism really wasn't as bad as the ones that we've learned for other addition reaction. It's pretty simple. Okay, I hope that makes sense. Let's go ahead and move on to the next topic.
1. Electrophilic Addition
2. Nucleophilic Substitution (SN2)
Additional resources for Halogenation
PRACTICE PROBLEMS AND ACTIVITIES (4)
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