The first new reagent that we're going to learn specifically works with acid chlorides. It turns acid chlorides into aldehydes. This reagent has a really long name. But all it is is it's a sterically hindered version of lithium aluminum hydride. Let me draw it out for you. It actually starts off exactly the same. Li Al. But then this is where it gets weird. Instead of having 4 hydrogens,3 of those hydrogens are replaced with what we call tert-butoxy groups. Then we draw parenthesis. Parenthesis, OtBut3H. As you can see, tert-butoxy groups because I basically have ethers made out of these Otbutyl groups and then I have only 1 hydrogen left over that's actually going to react. The other ones don't. The other groups don't. This molecule even though it looks really complicated, it's just going to be a version of lithium aluminum hydride that adds one equivalent. I'm going to get aldehyde instead. What I want you guys to draw in this blank up here is just that what's the thing that's making it hindered? That we've got these Otbutyl groups times 3. We're adding those to the LAH to make it a lot less reactive. That's the first one. Unfortunately, you do have to memorize this. You have to memorize how to draw it and what it works with. It specifically works with acid chlorides. That's it for that one. Let's move on to the next free agent.
DIBAL - Online Tutor, Practice Problems & Exam Prep
Why LiAlH4 doesn't work
LiAl(ot-Bu)3H on Acid Chlorides
Video transcript
DIBAL-H on Esters and Nitriles
Video transcript
This next reagent is also kind of random, guys. It works with esters and it works with nitriles. Let's draw that. What it's going to do is it's going to turn esters and nitriles into aldehydes by adding only one equivalent of H. The name of this reagent is weird. It's called Dival H. What the heck does that stand for? Dival H, the long name, I will give you the long name. It's called diisobutylaluminum hydride. Hence the name Dival H. This reagent is a pretty big sterically hindered reducing agent that's going to work with these 2 functional groups and it gives us aldehyde. The only thing I was going to do extra, I mean really we just have to memorize it. I'm not going to show you the mechanism. But I do want to show you the way it looks. It's just going to be an aluminum. I'm sorry, not a nitrogen, an aluminum with diisobutyl groups attached to an H. Again, you can see what I mean by sterically hindered. Isobutyl groups are pretty big. It's got 2 of those around. That's going to influence its reactivity. One last thing about this reagent. It does also require a hydrolysis step. Typically, you'll see it written as Dival H and then water. Water is required to hydrolyze the intermediate and make it into the final aldehyde. Now you guys know the 2 new reducing agents for this section. We've got the sterically hindered version of lithium amide hydride is one of them and we've got DIBAL. Let's move on to the next topic.
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