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Hey, guys, In these next few videos, we're going to be discussing a mean calculation and by the word a mean, I'm not talking about an angry ALC elation. Obviously, I'm talking about the functional group A means. So now that we've settled that one, let's go ahead and get into the reaction. So, guys, a huge part of this section of your text the amines portion of your text is gonna be trying to figure out how to synthesize primary means. Primary means are useful for lots of different applications. And we're always trying to figure out what's the best way to make a primary amine of my choice. Well, the go to reaction that we would possibly think of is, why don't we use an ocular Hey, lied. Because if you look at it, I mean, it's got a very nuclear filic. I'm just gonna put here n you negative A nuclear filic lone pair. Now there isn't a full formal charge on this molecule it all I'm just using the n u negative as my symbol for a nuclear file. I've gotten Electra file, which is the carbon that is attached to my hey lied. So this opens up for a reaction that we learned a long time ago when it's one of those mechanisms you're never allowed to forget. Backside attack or s N two. OK, so theoretically, we can make primary means through the reaction of an amine and inoculate Allied. So let's go ahead and just talk about this for a second. I'm not gonna draw the whole mechanism, but we're just gonna draw like an abridged one here. You would have the lone pair doing a backside attack. Um, because on my Electra Philip Carbon, I would kick out my leaving group. What you would wind up getting just from this very first reaction is you have an NH three that's now attached to a three carbon chains. I'm just gonna write 123 Okay, now, one of the problems with that is that you're gonna have a positive charge. Okay, because now you have an extra bond to that nitrogen that wasn't there before. That's why we always run this reaction in a basic environment, something like anyway, H the O. H negative is gonna serve to deep protein, ate the products. So then hopefully by the end, we're actually getting our primary means. So I'll just draw that one more time. NH two with our three carbon chains So everything seems pretty straightforward. It seems like this should be our go to reaction for making primary means because it's so easy to use. I could just literally throw any alcohol highlight in their asses long as it was primary or secondary or metal. And I could get in s and to remember, that s and twos or tricky. They don't work on tertiary alcohol highlights because the leaving group is kind of two backed up. It's too difficult to access, but we've got another problem on top of that, guys, it's not just that s and two has its limitations. One of the biggest problems of this reaction is that we still have a nuclear filic lone pair at the end of the reaction notice that your product is Justus nuclear Filic as it wasn't the beginning. So what we get is a possibility of multiple calculations on we're gonna find is that the predominant products in these reactions is gonna be a poly alc elated. I mean, which kind of sucks if you're trying to make a primary? I mean there is a way to counter act that which is to use excessive amounts of a mean. So if you could drown the solution with tons of your mean and then have very little of your ocular hey lie that reduces the chances of getting multiple are groups on the same nitrogen. But it's still quite a limiting reaction, and one that we're not gonna find very synthetically use synthetically useful. We're going to rely on other methods of making primary means for this reason. So let's go ahead and look at the next video. In the next video, I'm gonna explaining the entire Polly calculation mechanism of Inamine.
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let's explore what this reaction would look like in a situation where there isn't excess. I mean, all right, so let's go ahead and just bring down that I mean, that we were using before we were using basically NH three. Right? And let's go ahead and react that with the same alcohol headlight we were using before. So let's use a Pro Bowl chloride. Okay, so anyway, so what we get in the first step is, in essence, you mechanism running this in a basic environment. So we're going to say is that you're gonna get and h to H now within our group and a positive charge. Your ohh would then deep Rotimi. And what you're gonna get as a result of the first step is you're going to get NH two with your propane group, and you're also gonna get I guess water right? And your c l minus is a leaving group. I'm gonna start omitting those as we move forward because it's not really that important. I just care about the organic products. So now we've got this primary amine wonderful. We start off with basically ammonia and now we have a primary amine now if this reaction stopped here, that would be awesome. The problem is gonna be that's not going to stop here. It's gonna keep reacting. So we're gonna wind up getting Is this reacting with my second equivalent of alcohol highlight? So I then take my lone pair, I react, I kick out the chlorine. Now I've got something. Looks like this. I just have to start drawing a little smaller to fit all this in. I'm gonna get a three carbon chain on one side. I'm gonna get another three. Carbon chain on the other to h is positive. That's gets deep protein ated because I'm in a basic environment and now I've got a secondary mean So guess what happens, guys, it can react again. So anyway, this reaction keeps on going, so I'm just gonna right arrow, arrow, arrow. Imagine what winds up happening towards the end. What you're gonna wind up getting is a nitrogen that actually has four Pro Bowl groups on it because it completely substituted every single hydrogen was deep protein ated, and every single bond is now an alcohol group. The problem with that is that that's not what I wanted. I mean, if you wanted a no Monium derivative. Great. This is the reaction for you. But this isn't very useful for me. If what I'm trying to get is a primary primary. I mean, this is very far from the mark, Okay? So just letting you know this is the reason that we're usually gonna stay away from a mean occupation, and we're gonna use some more, uh, interesting, unique ways of making primary means that are more controlled, that air in a more controlled setting. Okay, so that being said, I do want to show you guys an example where this reaction may be helpful. So go ahead and do this practice problem. This just, you know, heads up is related to your, uh, basically a romantic city section. So if you haven't gone through aromatic reactions yet, you're gonna be a little lost here. Um, you can always return to this after, um but just keep in mind that is going to draw from what we learned in your aromatic section of your text. Okay, So go ahead and try to figure out what to re agents would be needed to make this transformation. And then I'll show you guys
Propose a Synthesis
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So we've got two transformations that we need to keep track of here. One I need to turn my tertiary amine. Okay, which would be referred to as an an allene derivative. Right, Because this is an Anna lean to our group, so it's an Antillean derivative. Somehow I need to turn my tertiary mean into a Quaternary Amine. You might have a better idea of how to do that. Now that we just went through this reaction might be giving you some ideas. When have you seen a co ordinary? I mean, before being made. Another transformation that I need to make is I need to add a chlorine to the meta position off the benzene because it's metta to the original group that was there. So we've got basically two reactions that need to happen. One of them is gonna have to be in a mean calculation because a mean occupations are really surefire way to get Quaternary means once you have a Quaternary, you can't keep calculating since the end point. So that's actually gonna be the perfect reaction for this. Now, over here to add the chlorine, that's gonna be an E s halogen nation or in E. A s coronation. Now, the question is, does it matter which order these air in or kind of just put them in any order? The order matters, guys, because right now, this is an O. P. Director. Okay? Aniline derivatives are Opie directors. They're one of the strongest ones that there is. Whereas notice my quaternary mean has what kind of charge? Positive. Do you remember what a positively charged substitution is gonna dio? It's gonna be a D activator. It's gonna be a withdrawing group. There's now an electron withdrawing group. It's actually one of the strongest electron withdrawing groups because that's a full, positive charge right there. And it's gonna be a meta director. So what? That shows, you guys is that a mean calculation is actually a sequence group. Okay. And again, this is all drawing from your air Metis ity section, but just letting you guys know that it is a sequence group because this group will can alter the sequence of the regents for synthesis. So, in this case, since I want meta activity, I want a meta directed product. I'm gonna go ahead and do my calculation first, the specific our group I'm adding is just the ch three. So I could just use, um, ethyl alcohol. Hey, lied. So I'm gonna use C h three. Um, c l Okay, now, normally, we would run in a mean calculation in base, so I would say Stage three c l and N A O h. But there's not gonna be anything to the protein ate here because I'm literally just adding the fourth our group on. So that's all I need. I don't need base here. In fact, if I put base, it's not gonna do anything. There's nothing to D protein eight. Okay, you would Onley use base if you were starting from a primary or secondary. Um, or metal. Uh, not method, but ammonia, ammonia or primary Mean or secondary. I mean, but if you're starting from a tertiary like this, then there's really gonna be nothing too. Deep protein eight. Now, the second reaction is gonna be the es college nation. So you guys remember the re agents for that? You got this. So c l two and F E c l three as my Lewis acid capitalist. So that is going to make my chlorine atom the medal position because now I have a strong meta director, and we're good. Okay, So hope that made sense. Guys, this is really the Onley synthetically useful application of amino calculation. We're not gonna use it a lot for synthesis because of the complications that we just discussed with Polly Calculation. All right, so let's move on to the next reaction.
Additional resources for Amine Alkylation
PRACTICE PROBLEMS AND ACTIVITIES (9)
- Rank each set of compounds in order of increasing boiling points. (a) triethylamine, di-n-propylamine, n-prop...
- In each pair of compounds, select the stronger base, and explain your choice. (a) HOCH2CH2NH2 or CH3CH2NH2 (b...
- Within each structure, rank the indicated nitrogens by increasing basicity. (c)
- Within each structure, rank the indicated nitrogens by increasing basicity. (a) (b)
- Rank each set of compounds in order of increasing basicity. (d) pyrrole, imidazole, 3-nitropyrrole
- Rank each set of compounds in order of increasing basicity. (c) aniline, pyrrole, pyridine, piperidine
- Rank each set of compounds in order of increasing basicity. (b) aniline, p-methylaniline, p-nitroaniline
- Predict the products of the following reactions: (a) excess NH3 + Ph-CH2CH2CH2Br →
- Propose a mechanism to show the individual alkylations that form this quaternary ammonium salt.