Organic Chemistry

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19. Aldehydes and Ketones:Nucleophilic Addition

Wolff Kishner Reduction

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General Reaction

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on this page. I want to discuss a specific reaction that hydro zones can undergo. And that's called Wolf Kushner reduction. So the Wolf Kitchener reduction is a reaction that completely removes carbon eels. Now, I'm not sure if you guys are already familiar with these reactions or if you've studied them yet. But there's two reactions that we've you learn in organic chemistry to that also, completely remove carbon eels. One is called Clements introduction that sound familiar, and the other one is called Theo's Towels plus Raney Nickel. Okay, well, it turns out, guys, that this is just gonna be another method. So there's a third method that we can use to completely get rid off a carbon Neil and turn it into an Al cane. Okay, now the way we do this is by using an ammonia derivative to make an Emmy and derivative. Let's see how what we do is we take a carbon eel erected with hydrazine hydrazine is going toe ad and Macon Imean derivative, specifically the Indian derivative that we make is called hydro zone. If you recall, Hydro zone is the combination of hydrazine with a key tone, so it's hydro zone Once you have your Haider zone, usually you would be done. Usually this would be the end of the reaction. Okay, it's reversible. But if you react this hydra zone in a base catalyzed environment, you're gonna get a completely different product. What you're actually gonna get is the generation of an end to gas, which I'll show you. You're gonna get into gas to evolve, and you're going to get an al cane. So the regions we usually use for this are some strong base. Anyway, H works just great. In your textbook, you might see K o H or to Turkey Talk side. It doesn't matter. It's just some strong base. Usually there is an alcohol present to help the reaction along. Now, this alcohol is not in the mechanism is just there to provide correct conditions for the mechanism to take place. Ethylene glycol has shown here is a really common one. And you need heat. You need some kind of heat to get the reaction going. Okay, so now what I'm gonna do is in the next video. I'm gonna show you guys the whole mechanism for wolf kitchen reduction.
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Mechanism

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Alright, guys. So when it comes to the mechanism of wolf kitchen reduction, there's two things that I want you to keep in mind. One, we're starting off with hydro zone, so don't worry about drawing that mechanism again. Oops. No age and each each perfect. Don't worry about drawing the mechanism for hydro zone because we've already done that. That would be an Emmy in reaction, so don't worry about that. What we're gonna do is we're gonna react this with base, okay? And there's two objectives that we're trying to do. Okay. One thing we're trying to do is we're trying toe ad. Each is to the m mean carbon. Okay, so I'm just saying that this is an Emmy derivative. So that would be this guy right here. Right? Okay. Another thing we're trying to do is we're trying to evolve and to gas. Now, if you guys don't know what into gas looks like and to gas is n triple bond and loan pair of lone pair. In fact, nitrogen gas is like 78% of the atmosphere is n two gas. So 78% of every breath you take tonight is an end to gas. Isn't that romantic? Okay, so we just drew that. So we're trying to somehow make a triple bond between those nitrogen. Maybe that will, those objectives will help you to remember this mechanism because it's a little weird. So the first thing we're gonna do is we're going to transfer a proton to the very bottom carbon. The way we do that is through a base catalyzed proton transfer. So my base is gonna grab an H that's going to cause a double bond to form here, make up on break a bond. If I make that bond, I have to break a bond. So then this double bond is gonna break. But what it's gonna do is it's gonna grab an H off of the conjugate of my base. Okay, so what I wind up doing is I wind up getting something like this. And now double bond end each. And now I have an extra h down here that I didn't have before. So notice that I just got closer to my goal in two different ways. One I was ableto add an age to the bottom Carbon awesome Two. I was able to get closer to putting a triple bond between my nitrogen. I'm trying to get a triple, Bond. Okay, by the way, this was called. This is my base catalyzed proton transfer. Perfect. So now what can we dio? We could do it again so I can react with another equivalent of base and do the reaction again. So I'm going to take away this age. If I make a bond, I break a bond. I'm gonna break a bond and make one to the end. And now that that nitrogen has three bonds with one on the bottom, it doesn't need any more bonds. So it's literally just gonna break this single bond and turn it into an anti on at the bottom. What this is going to do? Is it going to give me the molecule? Looks like this. Now, I have a lone pair here, so have a negative charge. Ivan, an eye on Plus, I have n triple bond n plus. I have water, which doesn't really matter, But notice that now this nitrogen gas is gone. Okay? It could just leave. It does. It's not tied back to anything. It's just gonna take off, okay? It's gonna go into the atmosphere. Now. This an ion, however, is very unstable. So this and I remember it had one h already. Right. Let's draw in that age, it was here. Okay, well, that and I am just gonna grab another hydrogen to regenerate that base. So what? I'm gonna get it. The end isn't gonna get and al Cane that now I added to hydrogen is too. So I get an al cane product. Plus I get my end to gas, and I get my base left over at the end. Cool. Right. So, guys, I don't know if your professor is gonna require you to memorize this. Usually with Wolf Kitchener when I teach. My students is recognize it. No. The re agents. It's not that often that your professor actually wants you to draw the whole mechanism, but I'm gonna leave that up to you and your discretion. Okay. If you have a very mechanistic professor that said you better know Wolf Kitchener, then you should learn it. If not, then just let this help you understand the reaction. I would focus much more on the reaction and the re agents more than the actual arrows. Okay, awesome guys, Let's move on to the next video.
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