Saponification - Video Tutorials & Practice Problems
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When you hear "saponification"just know that this is a base-catalyzed hydrolysis of an ester. The mechanism and final product are slightly different. Let's take a look.Â
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Mechanism
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Hey guys in this video, I'm going to teach you about the base catalyzed extra hydraulic sis reaction or better known as the PSA pontification reaction. So guys PSA pontification is just a base catalyzed hydraulic assist of an ester, meaning that if I have an ester and expose it to water and base as a catalyst I'm gonna hide relies that Esther. Okay, now we would expect to get a car looks like acid, but if all you have is base present, you're actually gonna yield a car box late and ion. And that makes sense because there would be nothing around to protein ate it. Okay, so in the absence of a proto nation step, you actually should end up with an own negative car box late or what's also called a carb oxalate salt. Okay, because that's that full negative charge. Okay, so just so you know, that is kind of like, you know, something that you should be aware of that. You need the protestation step to get to the car oxalic acid and now we're just gonna go through the mechanism. I'm not sure if you've heard me say this before. But in general guys in organic chemistry, a base catalyzed mechanism is always easier than an acid catalyzed mechanism. So this is actually gonna be a very straightforward mechanism. Okay, let's go ahead and assume that I'm gonna be using, right, I'm using water and base. So I'm just gonna use always negative. Okay, that's my base and in my first step, I'm going to do a nuclear filic attack because you know, this is already strong enough to attack that partial positive. I don't need to do a proto nation and draw resonance structure to make that carbon active. It's already active because I got a negatively charged nuclear file. So boom and boom I'm going to get a tetrahedron intermediate. We've seen this before. So I've got O. Negative. I've got O. R. I've got O. H. And I've got my carbon. Okay awesome. So then we're gonna go ahead and we're going to reform the double bond. We're not gonna protein eight because this is nuclear like a ceo substitution. This is an N. A. S. Reaction. Right? So we're going to kick out a leaving group now which one do we kick out? Do we kick out the O. H. Or the O. R. Or the our group? And we could kick out the R. But that would be. So anyway O. H. O. R. Um Well it really depends on the way you want to draw which direction you're trying to go in. Since I'm trying to go towards hydraulic sis I kick up the O. R. Okay so what that's going to give me is a molecule that looks like this now. It's a car looks like acid. Started thinking oh I did get a carb oxalic acid But no because you're gonna have O. R. Negative around now and that are negative will dip rotate it. Okay so then we're just going to get our car box late as a product. Okay Plus alcohol and that's where it ends. That's the end of the mechanism. Now, if you protein ate it afterwards, then fine, you can get a carbolic acid, but you need that protein ation step to get there. Okay? So as you guys can see super easy mechanism compared to the acid catalyzed version. So let's move on.
Mechanism:
I hope you guys enjoyed that super easy mechanism:). Ready for the next topic?