Hemiacetal

In this next page, we're going to discuss one of the products that happens when a neutral alcohol attacks a carbon eel and that's called Hemi Assets House. So, guys, let's just start off with one big disclaimer that disclaimers that technically, the word ass it'll is used to describe the product oven alcohol and an alga hide while the word key towel is used to describing alcohol and a key tone. Okay, However, it turns out that professors air lazy, even textbooks are lazy and they prefer. Since alcohols and ketones are essentially the same molecule in terms of their reactivity and nuclear fill, it, like addition is identical. Instead of using the distinction of a total kettle Hemi s hotel heavy key tell instead of saying all that, we're just gonna use the ass. It'll version. Okay, so whenever you see one of these gem die ether products because notice that the in product oven a settle reaction is they have to ether groups, okay? And they're in the general position there, general. Okay, Well, whenever you have this, we're not gonna worry about the our group so much. We're not gonna worry. Was it originally an Al the height or a key tone. I don't really care. I'm just gonna call it in a subtle even though, technically, it might be a key towel. But it's really like an industry standard thing where professors are not specific about the difference between and as to tell him the key. Tell now if your professor specifically always makes that distinction, then by all means go with what they're saying. But I'm just letting you know that even like online homeworks and a lot of textbooks don't really care about the difference between and asked Allah Makita Awesome disclaimer over So you guys should know this by now. Headmaster towels are Onley stable when they are cyclic or when they're a ring form. So here I have another picture of a cyclic Hand me a towel. Notice that I have a central carbon that has the four groups that I'm looking for. Notice that what is the heaviest hotel? Ah ha Master tells a functional group with either to ours or two. H is or mix, it doesn't matter, and in ohh and an O. R. In a general position. So in alcohol and ether in a general position that's a Hemi asset Tell notice that this molecule is also heavy as to tell Because I've got my age I've got my are I've got my o h my alcohol and my either my o r Okay, so when it's a cyclic having to tell your stable But if it's not cyclic, then you're not gonna be ableto end up at the headmaster. Tell So let me show you guys the general overview of this reaction. Well, it turns out that when you react to carbon ill with one equivalent of alcohol, you're going to get what we call a hammy as a tell when you acted with the second equivalent of alcohol, it's gonna be called in a settlement. It's gonna make that general die either. Okay, the mechanism for the first step and for the second step is almost identical. So the only way to really get it to stop at the Khenyeza towel is to make that cyclic version because if it's not cyclic, it's just gonna pass straight through Khenyeza, tell stage and go straight to asset tell. Okay, so I hope that's making sense so far. Now, what I'm gonna do in this next video is I'm gonna show you the exact acid catalyzed mechanism to create a Hemi hospital

another disclaimer before we began. The mechanism that I'm about to show you contains a resonant structure, as you can see here, we're gonna fill this one out. I like to add resonance structures into my mechanisms because I think it makes it more clear where the arrows are being moved to. Okay, The only thing is that your professor may not use a resident structure. Your professor just might decide to push the arrows without it. Okay, If that happens, it's okay. You can draw it his way, her way. You could drop my way. It doesn't matter, because in the end of the day, as long as the arrows we're going to the same places. It doesn't matter if you add a resident structure or not. This is gonna be true with a lot of the mechanisms and clutch prep. I go out of my way to try to make the mechanisms extra clear. And your professor might not really be explaining every arrow, So feel free to draw it my way, even if it's slightly different than the way your professor drew it. Just know that the arrows air being pushed the same way in the end So it's OK that you draw my mechanism, which it should be equivalent to the one your professor is drawing. That being said, why don't you help me out with what the first step of this mechanism is? Since it's acid catalyzed. What's the very first thing we should be doing? Pro nation. Okay, so the very first thing we're gonna do in an acid catalyzed mechanism is protein e. Okay, Now notice that my acid in this case is a protein ated version of alcohol. What I'm essentially using is R O H two positive. Okay, You could have used any acid source. Guys, it doesn't have to be that you could have used h plus, you could have used h +30 Plus, I'm just doing it like this because then the Conte it's gonna be more make more sense for you guys, the Conte of base. Okay, but you could use any other acid source. Okay, So what that's gonna make is a resident structure because I'm gonna get a positively charged oxygen. But we know that this double bond could join the oxygen to make a lone pair and then I would get a formal charge on the carbon. Okay, so I like drawing this resident structure because it makes it clear to me that that carbon is now very Electra, Filic, even Mawr Electra filic than it was when it was un reacted. So noticed that the whole point of the acid catalyst is to make this carbon even more reactive than it was before. So reactive, in fact, that alcohol is gonna want to attack it. So that's the next step, guys. So the next step is what we call nuclear feel like attack. I'm just gonna put n a nuclear feel like attack. So nuclear feel like attack is going toe attach the O make a new single bond, and we're gonna get a protein ated version of an ether attached to that central carbon. What do you think the next step is, guys de pronation. Okay, so we have to regenerate that catalyst. I'm gonna take my alcohol, my neutral alcohol. And since I start off with an alcohol acid catalyst, I need to regenerate it. So then I would just grab the h and lo and behold, what do I have it? The end. Now I have my ohh maior, my h and my h. Okay, on top of that, I have my catalyst still there. Okay, So awesome, guys. So that is a Hemi, A subtle right. And I always like to draw it in this cross structure because I, like Thio, always keep it consistent in terms off what I'm looking at. So that when I try to recognize the Function group later, I always just put it into that cross. And I'm like, Do I have all the groups that I need? Just a little peculiarity of mine. Okay, so anyway, that was the acid catalyzed mechanism to get toe. Ahem. Yes, it's not bad at all right now. Are we going to stay there? No, because this heavy metal is not cyclic the way I drew it. So this semillas tell is either gonna go back to the original carbon eel or it's gonna keep reacting with alcohol to get to in a settle. More on that later. Now, in this next video, I want to show you guys the base catalyzed version of the same reaction

as an overarching principle of Carbonell chemistry. The base catalyzed mechanisms for reactions are almost always gonna be easier than the acid catalyzed ones. The reason is because in acid catalyzed, we're trying to protein e d protein e to make things reactive for base catalyzed mechanisms. The region is already gonna start off reactive because you're making it a strong nuclear file and specifically for ketones and Alba hides. We know that strong nuclear files can do nuclear filic addition. So that just means that this reaction here that I'm gonna show you it's just a nuclear feel like addition. Reaction. Okay, so what happens? I'm my nuke level is O. R negative. Why? Because alcohol in the presence of a base remember this base catalyzed is going to react with the base to give me an oxide. Oh, are negative. Okay, So that oxide, since it's a negatively charged nuclear file, can do nuclear Philip condition on its own, just like any other negatively charged nuclear file we've worked with. So I would go ahead, attack the Carbonell Carbon, make my Tetra hydro intermediate, and I've got that own negative I have to take care of, But that o negative. Can protein ate with the conjugate acid of my base or of my nuclear file? So then I could just grab one of the h is to regenerate the base that I would have lost in the other prior reactions. Okay, so then what I would wind up getting is I would get my Khenyeza tell again I have my ohh on one side my o r on another, my h my h and I've got some Oh, are left over that can react with another carbon. You Okay? So guys hope that made sense. This was a whole lot easier than acid catalyzed So let's move on to what happens in the second step, which would be a settles.