Show how each of the following compounds can be synthesized fr...

Question

Show how each of the following compounds can be synthesized from benzene:

f. m-xylene

Accepted Answer

All right. Hi, everyone. So for this question, let's show how the following compound can be prepared using the given starting material and any necessary reagents. So our starting material is benzene. And by the end of this process, we've gone ahead and installed two ethyl groups to our benzene here. Yes. So because we're installing functional groups to benzene which is aromatic. This is going to be an example where we rely on electro phytic aromatic substitution, right? So what I'd like to bring to your attention as well is that our ethical groups here are meta to each other. And that's a little strange, right? Because recall that alco groups are Ortho para directing. So that means that we cannot install these ethel groups directly, so to speak, right? Because what we have to do first is we have to install a meta directing group to make sure that we get the substitution pattern that we want, right? And then from there, we can modify it as needed to end up with the E O groups that we see at the end of this process, right. So I'm going to start off by drawing our benzene on the bottom here because our first step has to be the addition of a meta director that can later be modified to generate an eyl group. Now recall that one such example is an AO group, right, because AO groups contain carbon that are incredibly um electron withdrawing, right, incredibly deactivating. So this Axo group can go ahead and be reduced to an ocular group via a wolf Kushner reduction. So we do have a game plan, right? And our first step is going to be the addition of our ASO group because that has the meta directing abilities that we need for this process. So because our substituent have two carbons each then for our craft isolation reaction, we are going to need um Aceto chloride, right? Because Aceto chloride has the two carbons that we need for our ethyl substituent at the end. So our first step here is going to be the addition of R aceto chloride and recall that we're going to need a catalyst, which in this case is A L C L three. But recall that we need a second step, right? And that second step is going to be the addition of water. So from here, we get our first substituent which is meta directing right now. Here it would be easy to say that we can go ahead and proceed with a Frito Crafts cul to get our second E O group in the metas position, right? But the thing is that recall that groups that contain Carbonis, right? Such as our ASO group here, they're incredibly deactivating, right? So because they're incredibly deactivating, then that makes Frito crafts cul population a lot more difficult, right? So instead a better approach would be to actually bromate the metas position and then modify it later on to get our E O group at the end. So in this case, bro, nation is favored because Fedora's Oculus is hindered in this case due to the deactivating effect of our A O group. So our second step is going to be, bro, like I talked about before and that requires elemental bromine with S A B R three as a catalyst. And that doesn't quite look like an F. So let me just fix that. There we go. So now we have two substituent in the meta position that we can go ahead and modify as needed, right? So let me just go ahead and draw them. All right. So now comes the modification of our substituent to get the ethyl groups that we need at the end, right? So let's go ahead and proceed with our A O group, which like we talked about before, can be reduced to an Alkie group using a Wolf Kish reaction reduction. So here when I react to my A O group with hydrogen hydroxide and he, I'm going to reduce my car bottle and I'm going to end up with simply an all kill group at the end of that process, right? So now here's my E O group at the end of my reduction, but I still have my bromine to take into account, right? And you can barely see it. So I'm going to move this a little bit upwards. That's better. All right. So now recall that we can go ahead and substitute our bromide for an A group using the Gilman reaction, right? So if we use a copper lithium substituent, we can go ahead and replace our bromine with that group using the Gilman reaction. So because we have an ethyl substituent, we need an E O group associated to the copper lithium reagent in question, right. So here recall that we actually need a ethyl copper lithium reagent. So it's two ethel groups and our copper lithium. So from here, right, our bromine is going to get substituted by one of our E O groups that's attached. So we have our group from our and now we have a second EHO group after our Gilman reaction. So this is going to be your final answer, right? And I know it was a lot, but there was a reason why we did everything right. So first of all, we began with FRITO Crafts isolation because we needed a meta director. First and foremost, then from there, we proceeded with bro nation of the ring because Friedel Craft's Oculus was hindered due to the deactivating effect of our A O group. And from there we reduced our cartel down to an A group using wolf Kish and then using the Gilman reaction, we substituted our bromine with another E O group. So this is going to be your final answer if you stuck around to the end. Thank you very much for watching and I hope you found this helpful.

Show how each of the following compounds can be synthesized from benzene:
f. m-xylene

Key Concepts

Electrophilic Aromatic Substitution (EAS)

Regioselectivity in Substitution Reactions

Catalysts in Organic Reactions

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