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19. Aldehydes and Ketones:Nucleophilic Addition

Organometallics on Ketones

19. Aldehydes and Ketones:Nucleophilic Addition

Organometallics on Ketones

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1

concept

Nucleophilic Addition on Ketones and Aldehydes

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Now that we understand nuclear Filic edition of carbon eels, I want to focus in on one of the most important nuclear files of all that can react in nuclear filic addition. And that's Organa Metallics. So, guys, I know Organa Metallics, freak. A lot of people out, they look weird. They've got a lot of atoms on them. Their medals. Um, but guys, these were some of the easiest compounds toe work with in terms of pushing arrows because organa metallics are just really strong nuclear files. So we're going to do the same things with them as we would normally do with anything that has a negative charge. Okay, Now, organo metallics do tons of different reactions. So if you want toe thoroughly, review organa metallics. You should go back to that section of your text, I mean, or of clutch videos. I've got plenty of videos on them, but what I'm gonna focus on right now is just really a refresher of what they do to key tones and Alka hide. So remember that we can use the letters R and M to represent any organic metallic because there's always gonna be some kind of our component some kind of alcohol group and some kind of metal. The two that were the most common in this section are green yards. So green yards would be our MGB are I'll be a green eared I'll write it down and organo lithium R l super Easy. And that's an organic Oh, with the, um okay. And guys, these molecules are both extremely similar in how they react, because they both have that ionic bond with extremely strong dipole towards the are okay, because remember that in your periodic table, the further you go towards flooring, the more election negative you get. Well, carbon is actually pretty close to full flooring, whereas thes group one and two medals are some of the least electra negative atoms possible. So they're gonna be it's gonna be a very ionic bond towards the carbon. Okay, so, Ionic, in fact, that we can write thes things ionized. Okay, we can actually write it as m I mean, as are negative. M g b are positive and the same thing for Organa With him, we could write it as our negative. L I positive. Cool. So that being said, these air just both the source of our negative. Okay, When that are negative, Sees the carbon, Neil. We're just gonna do nuclear feel like addition. We're gonna attack the partially the partial positive carbon Move the electrons up. What we're going to get is a tetra hydro intermediate o negative are one are too. But now I have my new our group. I just call it our since that's the one that I just added. And I mean, that's such a huge role. Intermediate would normally stay there, but these air usually followed by a pro nation steps, So I don't know exactly what the pronation step would be, but I'm just gonna put some kind of h a some kind of pro nation would occur and you would get your substituted alcohol. Okay, so you get Ohh. Are one are to and our that we actually add. Okay, so just a reminder. Guys, you should have worked with organo metallic before in this course, but this is you know, in case you forgot, this is really what you need to know. For this section, you need to know how to add an organo metallic taquito and to an alto hide, you're always going to get alcohol product and you're gonna get a new our group attached to that tetra hydro carbon in the middle. So that being said, what do you guys take a look at the molecule below and try to do the whole reaction, Draw the mechanism as well, and then I'll show you guys the answer, so go for it.

2

example

Organometallic on Aldehyde

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All right, So for this reaction, the first thing to do is draw your charges. You have to remember that your C six h five is gonna be negatively charged and your MDBR is gonna be positively charged. So I know this looks strange, but in actuality, what we're really dealing with is we're almost It's almost like having a benzene nuclear vile. We pretty much have a negative charge just on that benzene ring. And then MGB are is hanging out like like like a cat eye on just like a spectator ion. Okay, so we're gonna get our nuclear feeling edition. We're going to attack. And what we're going to get is a tetrahedron Intermediate that Tetra Usual Intermediate will have an O negative. It will have my new benzene ring attached. The fourth group is that there was a hydrogen there, right? There used to be a hydrogen. It's still there. Nothing changed. And usually, guys, if you're stopping at the Tetra Hydro intermediate like, let's say that the second region wasn't there, then many times, the way that you might see in the text or your professor might write it is that the MGB are well actually attached to the Oh, because one is negative and one is positive. So your t I Tetra hydro intermediate A lot of times will just be written like that, but we do have a protein eating agent. In this case, it's NH four cl. This is a very common protein eating agent for green yards and for organ metallics. Now, at first glance, guys, it actually looks really weird because you got N h four c l. It almost looks like nitrogen has five bonds, but that would break nitrogen octet, right? It could only have four bonds. How are five things attached to nitrogen? Well, guys, it's not really like that. What it is is that you've got your nitrogen with your four h is and that nitrogen is gonna have a formal charge because it's unhappy with the number of valence electrons. It has it once five and has four. So then the cl negative will be hanging out associated with the NH four positive, but it's not actually gonna be attached by a bond. Okay, awesome. So this promenading agent guys is going to get rid of the negative charge on the O and give us our eventual alcohol and alcohol. Looks like this with our benzene ring. And you've got your NH three. And I mean, it doesn't really matter. Guys thes other by products are not really of our concern, but you're MGB are really is just hanging out with a positive charge. Okay, Um and you could you could attach it to the C l if you wanted. The cl has a negative, so that would be fine, too. Okay, awesome guys. So that was it for that mechanism. What's been one to the next topic?

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Problem

Problem

Provide the major product for the following reaction.

A

B

C

D

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Problem

Problem

Provide the major product for the following reaction dealing with the Grignard reagent.

A

B

C

D

5

Problem

Problem

Provide the major product for the following reaction dealing with the Grignard reagent.

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Additional resources for Organometallics on Ketones

PRACTICE PROBLEMS AND ACTIVITIES (4)