As the name implies, these reactions add hydrogen which reduces π-bonds to alkanes.
General properties of catalytic hydrogenation.
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Alright guys and we're gonna talk about in addition, mechanism that some of you guys might already be familiar with. But regardless, we're gonna talk about it in this section because it has to do with addition. And that's called catalytic hydrogenation and also Wilkinson's catalyst. So let's go ahead and check it out. So basically, catalytic hydrogenation is a way of adding hydrogen, two double bonds. So remember that I said that any addition reaction is a reaction that could take one pie Bonnie to make to Sigma's. Well, actually, one of the easiest ways ways that you could do that is just to say, Let's take that one pi bon and make two hydrogen bonds out of it. Okay, that would still be in addition reaction because I'm taking one pie and I'm making to signal bonds, alright. And that's what happens with this with these both of these re agents. Okay, so how does this work in general? Basically, we're gonna have a double bond or triple bond, and whenever you have one of those were just gonna add as many ages to it as possible. So what that means is that the product of these reactions is simply gonna be Al canes. Okay, so we haven't learned a whole lot of reactions that make Al Cain's. This is one of them because you can take double bonds and triple bonds, add hydrogen to them until they're fully saturated and become Al Keynes. Alright, so the stereo chemistry for this reaction, both of these is gonna be sin addition. And what that means is that your end products would be sis products. Okay, What that means is that your hydrogen are gonna add from the same side of the dope on at all times. And why is that? Because it turns out that are intermediate or the thing that's going to catalyze this is gonna be a metal catalyst, okay. And that metal catalyst is gonna come in and it's gonna coordinate The H is to be on one side of that double bond. So that's why you're always gonna get Sin Edition. All right, so now for these two things, I'm actually gonna kind of ignore them. There's no carb, Okada, and so I'm not gonna expect to arrangements. And then I'm adding two of the same thing. I'm always adding to ages so I don't really have a choice between Mark and Anti Mark. In fact, that's not really gonna apply since I'm adding two of the same thing. All right, so let's go ahead and see the general reaction. The general reaction basically looks like this. I have two different mechanisms and two different re agencies do the same thing. This combination of re agents here is called catalytic hydrogenation. Okay, how do you know that it's catalytic hydrogenation? Because you've got h two sorry, little crash accident there because we've got hte to with a metal catalysts such as nickel, platinum or palladium. Whenever you c h two with one of those three, that means it's gonna be a catalytic hydrogenation. Okay, But there's also another re agent that does a very similar reaction. And that's if I have hte to over what's called rhodium. It's if this is the Wilkinson's catalyst. Okay? I'm just gonna write that here. Wilkinson's catalysts, okay, and the Wilkinson's catalyst is really going to do the same exact thing. Just using a different metal catalyst is gonna a rhodium and then three try fennel foss fiends and a chlorine you don't need to build to draw this What's important is that you just recognize that this is gonna do the same thing it's gonna add to H is for every double bonded encounters. But it's not gonna do anything else to anything else. So that means that my general reaction, what I would expect is that I get the same carbon backbone as I had in my beginning, I would get a single bond there. Even my alcohol doesn't change. Nothing changes about that. The only difference is that now, instead of having that double bond on this side of the molecule over here now, I'm just gonna have to h is. So, in fact, I would just draw it like that. I don't need to draw the h is because h is air implied. Okay. And then over here, what I would expect is that I would just have a single bond. Why is that? Because basically, there were two pi bonds here. What that means is that I add two hydrogen for every pi bon. So I would have added hydrogen here hydrogen here, and then I would have also added hydrogen here hydrogen here, and that's what I get at the end. What I get is two. Hydrogen is here and well, I'm sorry. One of each color one there and one there. And then I would get a hydrogen there and a hydrogen there. Those are the four hydrogen is that were added through my two hydrogenation or Wilkinson's catalyst reactions. Maybe you're wondering, Hey, but Johnny doesn't this carbon needs have three h is Yeah, Does it has that last H that came from the original compound? Remember, there was always one h at the end to begin with. That's that H right there. But now what I did was I added to Blue H is from the first equivalent. And then I added to read H is from the second equivalent, basically giving me an Al cane as my end product. Does that make sense? Cool. So what I want you guys to do now is I want to just provide the products for the following reaction. That means you have to recognize what it is and then think about the stereo chemistry if it's required and try to draw the end product. Now, notice that instead of using H two amusing D two. But that's really the same thing because remember that deuterium is just heavy hydrogen. So go ahead and try to draw the end product for this. And then I'm gonna go ahead and explain it to you guys, so go for it.