Give the structure of the repeating units in the polymers that...

Question

Give the structure of the repeating units in the polymers that are formed in the reactions of the following compounds.

a.

Accepted Answer

Hi, everyone. Let's take a look at our next problem. It says, determine the repeating unit structure of the polymer formed from the ification reaction between ethylene glycol and terreal acid. So let's think about what ification reactions are especially with in the case of forming polymers. And then we'll look at the specific reaction we're given. So our ification reaction involves the reaction of a carboxylic acid and alcohol forming an ester and water with a hydrogen or with an acidic catalyst. And we remind ourselves that the carboxylic acid has that structure of R bonded to a carbon group and that carbon carbon then bonded to, oh and our alcohol is then hor prime resulting in ester with a structure of R boat to the carbonel group and then on the other side of the carbon carbon or prime. So the oxygen from the alcohol binding to the carbon carbon with the elimination of the oh from the carboxylic acid and the hydrogen from the alcohol. So how would this work as a polymerization reaction? Well, if we have a molecule with two carboxylic acid groups, one on either end and two, another molecule with two alcohol groups one. On either end, you could just keep reacting one after another, alternating these molecules linking them together in a chain. So we would expect that our two chemicals were given would be dye alcohols and dic carboxylic acid. So let's look at ethylene guy call and we have common names here. So we may need to look up the structure of those molecules. And ethylene glycol is ho and then two carbon ch two ch two. And then, oh, so that's our dye alcohol. And then terreal acid, again, we may need to look that common name up is our dic carboxylic acid. And it's basically a benzene ring with two carboxylic acid groups in the pera position. So Hooc and then our benzene ring, which I'm just gonna draw in the form of the hexagon with the circle in it to indicate the benzene ring just to make my drawing a little faster. So now we need to determine what is the repeating unit here. So since I have my reaction written in the form of carb sic acid first and then alcohol, I will draw my Teric acid in its form. So we have Hooc Well, that's the beginning of the molecule, but we'll kind of take that away later because again, we're going to focus on the repeating unit. But first, I'm writing out the reaction in the way I've focused on above just to kind of get it going in a way. So I have hooc my benzene ring and then I have my carbon group, which then I've left off. Oh, because as I recall, it's my carbon carbon that reacts with the oxygen of the alcohol. So after my c double bau now I'm going to have an oxygen and that oxygen is from my ethylene glycol. So then the next part of the molecule will be the two carbons. So the ch two ch two from the ethylene glycol. Now we have another alcohol group and again, we'll have oxygen, but this is now reacted with the carboxylic acid on the next Teric acid. So there's no hydrogen, the hydrogen gets eliminated and we have a bond to the next carbon carbon. So see double bond o and we go into our next benzene ring, our next carbonel group c double bodo that's of corresponded to the oxygen from the next unit of ethylene glycol ch two ch two oh and so on and so forth. So let's look at what is our repeating unit. For instance, we've already put two molecules of each in here. If our repeating unit, we want to just show one molecule of each. So again, the bond between them will be between the carbonyl group of my tap folic acid and the oxygen of the ethylene glycol. So I'm going to look at the first where I first started this and I'm going to draw my bracket just in between that bond between the carbon carbon and the alcohol oxygen. So I have my open bracket there with the line going through it. And then I just want one single repeating unit. So I've started with Ethylene Glycol. Then I have the terreal acid. Now, my closed bracket goes again between the carbonyl carbon and the oxygen oxygen, excuse me, of the ethylene Glycol. So there's my repeating unit within brackets. Now, och two C h2o C double V to an O, benzene ring, C double V, an O. And then I put a subscript N and now I'll just take my eraser and erase the portions outside of the bracket. Again, I put them there just to kind of in my mind, keep track of how this molecule is coming together. But now I'm down to my repeating unit and you see the, at the either end I show the links from the oxygen, the links from that carbon carbon is sort of extending through the brackets indicating that that's where the link to the next repeating unit will be. So we got our repeating unit of Ethylene Glycol and Terreal acid. It's within brackets. And then we put the little subscript N to show that we can have however many units our polymer is long. See you in the next video.

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Give the structure of the repeating units in the polymers that are formed in the reactions of the following compounds.

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