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Organic Chemistry

Learn the toughest concepts covered in Organic Chemistry with step-by-step video tutorials and practice problems by world-class tutors.

12. Alcohols, Ethers, Epoxides and Thiols

Making Ethers - Acid-Catalyzed Alkoxylation

Same reagents as acid-catalyzed hydration, except with alcohol as the nucleophile instead of water.


The Mechanism of Alkoxylation.

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Another method for making ethers is called acid catalyzed Al Cox elation. And it's gonna be very similar to another reaction we've learned before, which is acid catalyzed hydration. Okay, really? This is the same exact reaction as acid catalyzed hydration on a double bond. Except for our nuclear file, we're gonna use alcohol instead of water. Okay, so let's just go through this mechanism really quick. I know it might have been a while, so I'm just gonna go ahead and start from scratch. I've got a double bond. Remember that Double bonds or good nuclear files, And I've got a strong acid. Okay, so here I've got my ass, and I'm writing it a little bit funny, but that's because it's gonna be easier. Thio protein it that way. And remember that the first arrow or the first part of this mechanism would be that my nuclear file attacks the h in my strong acid. Okay, my sulfuric acid. What that's going to give me is that's gonna wind up giving me a Carvel cat iron that looks like this with the H attaching over here. Now, this h I'm gonna go ahead and ignore it for the rest of this reaction because you don't need to draw. H is right, but just wanted to show you where it you know where it attached to. So I've got that Carvell cat I in there. Um do I go ahead and nuclear physically attack it. What should I do? I need to shift it. Right. So at this point, we would do a Carvel cat and shift because remember that carbon patterns will shift any time. It's possible for them to move to a more stable location. In this case, would this be a metal shift or ah, hydride shift? It would be a metal shift because I Onley have methyl groups adjacent to this Carvel Catalan. So I'm just gonna right here. It's a 12 c h three shift. And what that's now going to give me is really a new looking molecule that looks like this with a carbon Catalan there. Okay, notice that really all that happened is that the CH three from the top moved to the bottom. And now my carb Acadian is on the left. It's tertiary. It's a lot more stable. So now this is the part where my nuclear file attacks now for acid catalyzed hydration. Water would have attacked, and I would have gotten alcohol easily. But now I'm gonna use an alcohol instead. What that means is that I'm gonna wind up getting an O R group instead of and O H group. So I'm gonna get here age ch three. There we go. Now, I did notice that I've been making an error here. Does anyone see what the error is? Okay with the air is that I had an h right here because I wanted to draw it in. And I've continued to draw that stick in both of these. That should not be there. If you did draw the stick, just put the h there. Just that you guys will know that that's supposed to be an H. But also, you could just erase that stick completely. That would also be fine. Okay, Now, this oxygen needs a formal charge, so I'm just gonna give it a formal charge. What do you think is the last step here? How can I De protein ate that? Well, I could just use the conjugate base of my sulfuric acid so I could use os 03 h negative and I can de protein eat. And what that's going to do is it's going to give me my ether. Plus, it's gonna give you my original sulfuric acid. All right? I know that I'm right over that, so I'm just gonna Oops. So I just kind of disappear really quick. There we go. Oh, gosh. Okay, we're having some technical difficulties. I'll move to the side. Just You guys can see that There's an ether R O r. And I have sulfuric acid present. Okay, so this is another way that we can use to make ethers. Let me know if you guys have any questions, but if not, let's do some practice problems.