Making Ethers - Acid-Catalyzed Alkoxylation

Another method for making ethers is called acid catalyzed Alkylation and it's going to be very similar to another reaction we've learned before which is acid catalyzed hydration, OK? Really this is the same exact reaction as acid catalyzed hydration on a double bond except for our nucleophile we're going to use alcohol instead of water, OK? So let's just go through this mechanism really quick I know it might have been a while so I'm just going to go ahead and start from scratch, I've got a double bond remember that double bonds are good nucleophiles and I've got a strong acid, OK? So here I've got my acid I'm writing it a little bit funny but that's because can be easier to deprotonate that way and remember that the first arrow or the first part of this mechanism would be that my nucleophile attacks the H in my strong acid, OK? My sulphuric acid what that's going to give me is that's going to wind up giving me a Carbocation that looks like this with the H attaching over here now this H I'm going to go ahead and ignore it for the rest of this reaction because you don't need to draw Hs, right? But I just want to show you where it attached to, so now I've got that carbocation there do I go ahead and nucleophilic attack it? What should I do? I need to shift it, right? So at this point I would do a carbocation shift because remember that carbocations will shift any time it's possible for them to move to a more stable location, in this case would this be a methyl shift or a hydrate shift? It will be a methyl shift because I only have methyl groups adjacent to this carbocation so I'm just going to write here it's a 1-2 CH3 shift and what that's now going to give me is really a new looking molecule that looks like this with a carbocation there, OK? Notice that really all that happened is that the CH3 from the top moved to the bottom and now my carbocation is on the left, it's tertiary it's a lot more stable so now this is the part where my nucleophile attacks, now for acid catalyzed hydration water would have attacked and I would have gotten an alcohol easily but now I'm going to use an alcohol instead what that means is that I'm going to wind up getting an OR group instead of an OH group so I'm going to get here H, CH3 there we go, now I did notice that I've been making an error here does anyone see what the error is? OK what the error 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 so 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, OK? Now this oxygen needs a formal charge so I'm just going to give it a formal charge, what do you think is the last step here? How can I deprotonate that? Well I could just use the conjugate base of my sulfuric acid so I could use OSO3H negative and I can deprotonate and what that's going to do is it's going to give me my ether plus it's going to give you my original sulfuric acid, alright? I know that I'm right over that so I'm just going to.... Ops so I'm just going to disappear really quick, there you go oh gosh OK We're having some technical difficulties I'll move to the side just so you guys can see that there is an ether ROR and I have sulfuric acid present, OK? 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.