Crossed Aldol Condensation

Hey, guys, in this video, we're going to explore what happens when you try to run an Aldo condensation on a mixture of different alga hides. So whenever you run a condensation on two different key tones or two different alga hides, mixed products are going to be difficult to avoid because what's gonna happen is that we've got two different emulates that air possible not within the same key tone or alga hide, but on different alga hides. So that opens up a big can of worms. Because, for example, let's say we have Aldo hide a that conform and emulate here and Al Dahabi that conform manipulate here. Well, we've got an issue because it turns out that once you form easily a A can react with itself to give you a right so a negative could attack a the actual D. The actual pro native version of A to give you a a negative could also attack. Be so the the non emulate version of B to give you a B condensation product B negative. So the inlet of B could attack a to give you be a which, by the way, a B and B a look like they're similar, but they're not. They're actually gonna be different compounds because you have different numbers of carbons in each and finally be negative. Could react with B to give you bebe. So what's gonna happen, guys, you're going to get this terrible like, pun. It's square off of algal products and it's just gonna be a disaster. Okay, Now, for the sake of teaching purposes, I am gonna fill in this Planet Square s. You guys can see all the possibilities, but typically, this is not something that we would ever do in a classroom. You would never draw all four algal products because it's just it's a synthetically useless reaction. No one wants that high of a mixture of products. But for the sake of learning, let's just see what each of these combinations would look like. And always remember that the first letter I'm using as the immolates I'm doing in late. Easily, easily, easily. So doing my whole left right thing. Let's start off with a B. And I am going Thio. You might need to grab some extra paper for this because it's gonna be ah lot. I'm gonna minimize this and keep this in the corner. I know I'm cheating. Okay. All right. So let's start off with a B so a b, you would look like this. And I'm gonna try to draw small. It would be that might easily looks like this. Remember that. I told you guys that you should draw your our troops facing down and you're an alliance facing towards the right plus B, which I would actually draw my h facing towards the left and my ch three facing towards the right. Remember that you want your smallest group towards the anti on. So what I'm gonna get is a product that looks like this where I have h carbon alcohol carbon. Okay. Now, for the sake of just drawing these quickly, I'm gonna be drawing the beta hydroxy carbon eels. But you guys know that you could also dehydrate thes. So let's put that one here and again. Dehydration product would probably be the more accurate one. Okay, Now, to make sure we did it right, we should count up our carbons to see if the number of carbons and A and B add up soon as the A has three carbons and B has two carbons. So I should have a five carbon product. Do I? 12345 Good. So at least I'm right with the numbers. Let's do a so a should be this usually same Italy plus this un reacted. Now notice really minor little detail here. Notice that on the electro file side, I kept the our group facing up. But on the only if you sit down guys, it doesn't really matter which way you face the electric outside. I'm just facing it up because that's what I'm normally used to seeing. The only one you have to be careful about is the one that's facing down because noticed that my products actually made sense because I made it face down originally. Okay, so I'm actually saving myself a ton of time by doing these things ahead of time. So I'm gonna do my mechanism again. Remember, these are all reversible arrows, guys. So again, my apologies. I'm kind of overlooking a few things here, but what we would get is h carbon a touch toe, O h. And now two carbons coming off the shame. Okay. See how that changed things. So this product would be This was a rights. This was H carbon. Oh, h carbon carbon. So now we should count up our carbons again to see if it's right. This one was a five carbon chain. Let's see the other one. Now, if it's a A, that should be three plus three. That should be 6123456 Yep, Six carbons. Count up yourself. Okay, so we've got two of these. Notice how they're different. I mean, they look kind of similar, but there's carbons in different places, so B plus a So guys be looks like this. Each metal plus a which looks like this. That's gonna give me a compound that looks like this carbon alcohol, carbon. So notice that this one let's just draw it first. So I've got my alto hide and I got my alcohol. I got my ethel because so this one b plus a should also be five. Is it +512345 Yes, it is. Now, guys, notice that now I've got a plus B and B plus a together. Are they the same compound? No. They both have five carbons, but they're slightly different. These are the kinds of terrible mixtures that you get when you do across Aldo. Okay, so just like that's what this is called cross Aldo. It sucks. You don't wanna do this. Finally, B plus B is going to give me that is actually the simplest one to draw and that I'm gonna do my mechanism. I'm going to get h alcohol, carbon, and that's going to give me a molecule. Looks like this. All right, So I should have four carbons. Do I 1234? Yes, because it's b plus B two plus two. Excellent guys. So, as you can see, this is literally a synthetic chemist nightmare. They do not want to see this. This is like what keeps them awake at night. Okay, not even a nightmare. They can't go to sleep. So how do we avoid this from happening? Well, one, if you have multiple immolates that air possible, it's just gonna happen, so don't do it. But that's what we try to do. If you're going to do a mixed reaction, are cross reaction, then on Lee work. Make sure that one of the immolates or one of them Sorry. Make sure that one of the Al Qaeda key tones is gonna be non Yunel Izabal. Okay, What does that mean? Non analyze Will Means it doesn't have an Alfa Proton gonna put your no Alfa Proton. If it doesn't have enough a proton, then you can't do anything about it. You can't make an equally out of it. So these air some great examples Formaldehyde. Does that have any Alfa hydrogen? No, guys, it has Aldo hide hydrogen is but you can't remove those. So this is this would be formaldehyde. Ben, Zelda, hide another great example. See how Ben's all the high doesn't have an Alfa hydrogen. And I mean, you could name this one. I guess it would be to to dime Ethel pro panel, right? I don't really care that you memorize all the different good non analyze herbal carbon eels. But you should just be able to visualize that. Hey, if it doesn't have an awful carbon or I'm sorry, an Alfa hydrogen, then that's a good candidate for across Why? Because then these air always gonna be forced to be always the Electra file. That means that they're always going to get attacked. So you will only get one product because what you're gonna get is your anally. Let's say it's a minus attacking this or attacking this and you're not gonna worry about B minuses. Well, we'll just be your anally attacking the electrical. See how that simplifies things. Cool, guys. So hope that made sense. Hope that didn't remind you too much of genetics. Let's move on to the next video.

Give the structure of the aldehydes or ketones used to create the product prepared by a crossed aldol condensation reaction. 

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Give the structure of the aldehydes or ketones used to create the product prepared by a crossed aldol reaction. 

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• B.
• C.
• D.

What product can be isolated from the following aldol condensation reaction? 

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• D.