Predict the products and propose mechanisms for the following ...

Question

Predict the products and propose mechanisms for the following reactions.

(c)

Accepted Answer

Hey everyone and welcome back in today's video. We are going to give the structures of the products and suggest a possible mechanism for the reaction shown below. We noticed that we are starting with the curb oxalic acid that has a hydroxy substitute print. And we are essentially treating it with a strong asset in the presence of heat. We may recall that specifically whenever we're using a strong asset in the presence of heat, and we have a reversible reaction that implies an astro formation. And especially because we have our carb oxalic acid group and our alcohol group in the same structure. So we will have an intra molecular information of an ester which is called lactose own. So let's see how that works. If we think about our mechanism, we are going to redraw the starting material. So that would be our bookseller casting group. Now we are going to add everything else. This is our starting material. We may recall that the world first step is the protein nation step at the oxygen of the carbon ill within the carb oxalic acid. So we are essentially taking that lone pair and we're showing that attacks step, oxygen will get protein ated here. Now, as we know, every step will be irreversible because we're looking at the formation of an ester. So we're going to use equilibrium arrows and here we are ready to do our protein ated intermediate. So we are just going to add that oxygen, hydrogen bond, oxygen will have a formal positive charge. Now, this is the step where the alcohol group will attack Carbonell, right, essentially because auction has a formal positive charge, we have residents. So this electric center is better than before. We have increased its electro Felicity. So oxygen from the alcohol group can now easily attack it. We are forming a bond, breaking the adjacent pi bond. And now essentially this is where we are forming our ring structure. You may notice that we're getting a five member ring with oxygen in it. So basically, if we label our carbon atoms, you will see that if this is our carbon number one, then we have 234 and the fifth atom is oxygen within our five member grain. So let's throw a five member ring and let's include oxygen in it. So that's our five member ring and now equal label our carbon atoms 1234 and let's add five for oxygen. So we may clearly see that oxygen is bonded to carbon number one. And at position number one, we will now have two alcohol groups. So that B O H another O H position number three has two method groups And oxygen five has hydrogen still bond. It's it. So we will have a formal positive charge on it. This is where water formed in the very first step comes in and the protein it's, it's so we're going to use water which will act as a proton except, er, so our next structure will be the D protein ated form of the previous one. We're just going to try it once again. And now let's simply eliminate that oxygen hydrogen bond so that we got rid of our former positive charge. We may also eliminate our numbers, right? We only use them for simplicity of drawing the ring. And now let's remember that the next step is the protein nation step. Once again, we're going to look at the two alcohol groups and we're going to use one of them in the Protein Nation step. So we're essentially capturing an additional proton from hydro ni um And in this step, we are forming our protein eight intermediate. I'm sorry, let's retry it. So now let's protein it that this oxygen will now have two hydrogen atoms bonded sit and therefore, it will have a formal positive charge. We're going to say H T O with a formal positive charge. And this is a perfect leaving group for us, meaning the adjacent oxygen from the adjacent alcohol group can essentially form a pi bond followed by the loss of water, right? Because it's a perfect leaving group for us. And from here we're getting our next structure. We are forming our carbon eagle group. Let's get rid of water. And then we essentially get double bonded oxygen, which is still protein ated, right? Because we have a wage. So auction has a formal positive charge and they were the last step in this formation corresponds to the deep protein Nation steps who are going to use water once again, which will act as a protein except er so the lone parent auction will attack, we are going to d protein ate it and this is how we get our final product. So from here, let's draw the final product, which is our lack zone. So we are going to remove that proton and this is our final product. We got our found product, we clearly see how the mechanism looks like. So the last thing we want to do is just to add our product. So if we go back to our original Reaction over here, we're just going to add our product for this one and we can just copy our product from the mechanism. This is the last one that we got. We may label this is our final answer, right? We were interested in the final product and the mechanism. So we've seen the mechanism, we understood that this reaction is the formation of a cyclic Ester or Laxton, right? Because we have strong listed conditions, heat equilibrium, we have our curb looks like acid and an alcohol in the same molecule. We have an intra molecular reaction. We saw all of our steps and we may conclude that the correct answer to the multiple choice question is the Thank you for watching and I will see you in the next video.

Predict the products and propose mechanisms for the following reactions.
(c)

Key Concepts

Lactone Formation

Acid-Catalyzed Reactions

Reaction Mechanism

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