Reducing Agent

to reduce the molecule means to increase the hydrogen content of that molecule. In order for reduction to take place, you need reducing agents. So in this topic, we're gonna explore what those different reducing agents are. All right. So, as you just said, the definition of reducing agent is anything that's gonna be used to reduce or add. Hydrogen is two molecule. Okay, Now, categorically, there's a few different ways we can use. Thes reagents are all gonna add hydrogen across pi bonds. Okay, because what we're doing here is we're gonna be taking double bonds, triple bonds, stuff like that, and we will be adding hydrogen is to them. Okay, unsaturated hydrocarbons and carbon eels are able to be reduced through. These agents can remember that unsaturated means that I don't have the total amount of hydrogen possible. So as we add, hydrogen were actually saturating. So just you guys know reduction is a form of saturation. Okay, though they're two different words that could be used on almost interchangeably. Well, usually in general say reduction. But some types of reduction caused saturation. Okay. Also, just another kind of tangent is that saturation and reduction are also caused by hydrogenation. Okay, so if you ever heard of any reaction, that is a hydrogenation. That's a reduction because adding hydrogen and it's increasing the saturation of the molecules. These are all words that you should really group together in your mind because we're gonna be using them a lot when we're in this topic. So I just want to show you guys the general mechanism of what's going on now it's going to depend particularly on the re agents. But basically to both regions that we're gonna learn about today are both simply a source of H minus ion, which is what we called Ah hydride ion. Okay, they're both a source of hydride and pretty much regardless of what the carbon you'll looks like today, we're gonna be reducing a lot of carbon deals, okay? And pretty much regardless of what it looks like, the hydride is pretty much always going to attack in the same way, which is a mechanism called nuclear Filic edition. Okay, now, in this topic, I don't need you to be a master of nuclear Filic Edition, but just kind of humor me as I go through the first few steps. Just see us can kind of get an idea of what's going on. My H minus attacks the carbon or carbon. There's a positive charge on that carbon because of the die pull pulling away from it, which makes the H attracted to it. OK, when I make that bond, Carbon doesn't like to have five bonds and wants to have four have to break a bond. So I move electrons up to the O. What I wind up getting is an extra h can't the bottom. That's the one that just attacked an O negative at the top. And that o negative winds up protein eating. Okay, so what I wind up doing is I wind up making an alcohol out of my original carbon deal, okay? And that's what the regents we're gonna learn about today. Do they all do something like this? All right, so let's go ahead and read a little bit more about reduction. Reducing agents are going toe add toe all of the pie bonds present. Okay, so that means that I don't need to say 10 equivalents of my reducing agent in order for you to realize that it's going to react 10 times if it can. We're just gonna blast away as many carbon eels as possible in this reaction. Okay, even if I don't put how many equivalents of my region I have. Okay. So that's why it says multiple equivalent of hydrogen will react if possible. Just think anything that hygiene will react with can react with it, will. Okay, so let's go over our first free agent. And there's actually a very important region in organic chemistry. We use it a lot in or go one and or go to. This is lithium aluminum hydride. L I L h four. It's also simplified. You could call it L A h. Why? Because it's lithium aluminum hydrate. Okay, so LH is like the strongest reducing agent we know of. It blasts pretty much everything. Okay, so it's gonna be able to reduce any carbon compound Carbonell compound into an alcohol. Okay, so let me show you guys what a typical reduction with LH would look like. All right, well, here you notice that we have an alga hide is an Al Qaeda type of Carbonell. Yes. Okay. So what I'm gonna do is I'm gonna wind up getting something. Looks like this the carbon stays intact. But now instead of that being a double bond Oh, it turns into an alcohol. Okay, now, you know, if you're wondering Well, Johnny, how would I know that that would happen? Well, first of all, you're always gonna goto alcohol. You're never going to go to less reduce more reduced than alcohol. Okay, but another way that you can think of it is that we're adding an equivalent of hydrogen. Because notice that before this direction happened, I had one hydrogen at the bottom, right that hydrogen is still there. But now what happened after the reaction is over is that I added one equivalent of hydrogen. What does that mean? It means I added one h hear. Oops. I want to use a different color so I could see that Ghani's blue one each year and I added one h here. Okay, so that's why I get an alcohol. Because I'm basically adding to hydrogen to both sides. And remember, that has to do with the mechanism. How one h attacks from the bottom and one h comes from the pro nation step. Does that make sense? Cool. So we're adding to H is which is this would be one equivalent of hydrogen. Okay, so let's look at this next one. How about if our functional group is in a ring? That's a little bit more tricky. This is an Esther, right? Is an Esther a type of carbon eel? Yes. Okay, so in this case, we're gonna wind up reducing both sides were gonna chop this bond right there in the middle because we know that this eventually has to become an alcohol. Right? And alcohols don't attach in a ring. You can't have an alcohol with two bonds on both sides, or that would be in either. It wouldn't be an alcohol, so we know that that bond is gonna have to break. And actually, what it's gonna happen is that we're just gonna get to alcohol's on both sides so I could count my carbons. I would say this is carbon one, 23 I'm gonna have a three carbon chain. Okay, But then both of the things on both sides will end up becoming alcohol. So on number one e, just trying to use a different color again on number one. I would get This is number 12 and three I will get alcohol. Were basically this dull upon Oh, just got to h is added to it Got in h at the bottom and in h of the o like I just drew in the first example. Does that make sense? So nothing's changed there. Now, what's different is that for molecule Adam three. It has an o coming off of it that it was just gonna get extra proton. So this one is going to become oh, H as well. Okay, so you wind up getting actually when you have a cyclic Esther like this cyclic Esther. Okay. You're actually gonna wind up getting what we call a dial. Okay? Now, do I care that you remember that detail specifically? No. But if you have learned about Dial's before, you know, this is an example of one. Okay, so that's the first thing LH strongest reducing agent. We know it's gonna basically transform every Carbondale. Let's move on to our next reducing agent. Okay, We also have something called a week reducing agent. Okay, Now, week reducing agent is gonna be very similar, except it has more limitations. Okay, It's on. Lee gonna be ableto add one equivalent of oxygen as opposed to more than one. Okay, so what that means is that and that's the That's the technical term. But what I really care that, you know, is that it's on. Lee gonna be able to reduce Alba hides and keytones. OK, remember, ch shows an alto hide. Okay, so what that means is that when you encounter a carbon deal that is not an alga hydra key tone. Nothing is gonna happen because N a B H four is not strong enough to oxidize. I'm sorry to reduce those reactions, those re agents. So we're only gonna be able to reduce Aldo Highs in key tone. So let's look at the products for the first one. Would n a B H four react with that Aldo hide? Yes. In fact, we're gonna get the same exact alcohol that we would have gotten over here in the first example. Same exact alcohol. Okay. Will it reduce an Esther? No, it will not. It is not strong enough. OK, so what is it not going to reduce? Let's go ahead and just list them out. It's not gonna reduce Esther. It's not going to reduce carbolic acid it's not going to reduce in amad. Okay? These are car box. Look, acid, I'm sorry. These are carbon deals that are too highly oxidized for the molecule to reduce. So any beach four is not gonna able to touch those. But it will be able to react with carbon deals such as ketones and altitudes. So the first reaction works. The second one doesn't. Overall reduction isn't that hard. You don't even really need to know the mechanism most of the time, you just need to predict the products and tell what NH four will react with. And what it won't remember that LH pretty much wracked with anything. Okay, so let's go ahead and do some practice problems.

Alright, guys. Now we're gonna be doing some reduction practice problems. Just remember to keep in mind the difference between L H and N A B H four. Remember, that one is strong and one is weak. I'm going to test you on both of those concepts right now, so go ahead and try to figure out the first problem.