Show how you would accomplish the following syntheses.
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Question

Show how you would accomplish the following syntheses.

(c) benzene → p-methoxybenzaldehyde

Accepted Answer

Hey everyone and welcome back into this video, we are going to learn how to solve the following problem, which asks us to show how the following conversion can be carried out using suitable regions. Now, if you look at our reaction scheme, the starting material is benzene and we are producing with oxy benzene. Now the most important thing here to understand is that aromatic compounds are not really so reactive. And if you want to add a substitution, essentially replacing one of the hydrogen atoms, because if you look at that this hydrogen atom bonded to the benzene ring has been replaced with any toxic group. This is not so easy to see. There's no actual straightforward way but let's keep it positive and let's think about what steps we can actually take. So first of all we want to make it a substituted benzene. Right. We want to have some sort of substitution to go towards the and a toxic group and to produce that epoxy benzine final compound to do that. The easiest way to add a substitution to benzene is the electra filic aromatic substitution. Right. What if we just start with benzene? And what if we want to replace that hygiene with chlorine, recall that one of such reactions is to use chlorine in the presence of aluminum chloride here, aluminum chloride acts as a lewis asset. So during the formation of the complex were able to replace that hygiene with chlorine and this is a very common reaction that you will see other using chlorine with aluminum chloride where iron three chloride, that's perfectly fine. Right? We are going to form our first intermediate and we can say we get our benzene ring and then we're simply adding chlorine at any position. Right? Because it's just mono substituted. Now, chlorine, even though it's a good leaving group for sp three carbon atoms that respondents an sp two carbon atoms. So we cannot really use some sort of an essence to reaction. So this is out of the question. Now, what we can do instead, we have to recall that there is a possibility to use sodium hydroxide. We want to add that oxygen atom somehow over here and then we will be nearly done. Right? So to get that oxygen atom, we may use sodium hydroxide at the presence of 35°C temperature. This is a bit of a longer mechanism in which we have an elimination addition mechanism. And what's happening here is that we're essentially replacing chlorine with oxygen. So what we're getting here is that we're forming that elk oxide online. Right, essential. First of all, of course, we're adding hydroxide to that position during the mechanism but the hydrogen atoms then transferred back to the adjacent carbon atom to restore automaticity. So that's why the final product here is the elk oxide itself instead of adding hydroxide here, right. We're not really forming fennel in this step and this is really useful for us because when we have our cock side, we simply understand that we want to add to carbon atoms to monetary oxygen. So we can think of a basic essence a reaction. Because now we have our nuclear file. This is a good nuclear file for us. We can perform an essence to reaction. Right? So why don't we use ethyl group bonded to a good leaving group? Let's suppose iodine. Right. We can use bromine or chlorine. That's perfectly fine. But iodine is probably the best because it's the biggest atom. So during that sn two reaction we would have in nuclear attack at the carbon pulled by the loss of the leaving group. Once again, this is in essence a reaction, right? And then we are forming our final product. We can say that when this reaction is over we get our final products. We can say that we're getting oxygen bonded to that ethyl group. That's how I found product you Toxie. Benzene. Let's just Individual all of the steps now in the main scheme. So number one was addition of chlorine in the presence of aluminum chloride. Number two, treating the resulting compound with sodium hydroxide at 35 degrees Celsius number three, which was our final reaction addition of ethyl iodide. So these three are our steps for the given commercial legislate, build them. Right? So let's recall everything that we did. Step number one we said, okay, we want to have chlorine bonded to the benzene ring because it's the most common reaction where we start adding substitutions to benzene. So adding chlorine in the presence of aluminum chloride formed our intermediate product, right, chloral, benzine. We treated it with sodium hydroxide at 35 degrees Celsius to make sure that we are now replacing this chlorine with oxygen, keeping in mind that the final product has oxygen. So we are already thinking about that essence, the reaction that we can perform, right? So when we get that oxygen, which acts as a good nuclear power, taking our primary substrate with two carbon atoms because we need to add two carbon atoms, a good leaving group. Once again, don't worry, you can choose bromine or chlorine that's perfectly fine. And then we get our product, we get the ether oxy benzene out of benzene. We steps here and that'll be it. If you have any questions, don't hesitate to leave a comment down below. And the correct answer to this problem is B thank you for watching

Show how you would accomplish the following syntheses.
(c) benzene → p-methoxybenzaldehyde

Key Concepts

Electrophilic Aromatic Substitution (EAS)

Ortho/Para Directing Groups

Formylation of Aromatic Compounds

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