Ozonolysis of an unknown alkene A gives the p...

Question

Ozonolysis of an unknown alkene A gives the products shown. Predict the product that results from hydrogenation of alkene A. [There are multiple answers, but only show the one with the 6-membered ring.]

Accepted Answer

Welcome back everyone. The Oceano thesis of an unknown LK X gives the products shown below X contains a five membered ring for the product act. If it reacts via hydrogenation, instead, we're given our reaction scheme where an unknown alkin reacts with ozone and then dimethyl sulfide to produce two carbonyl compounds. Let's remember that osos reaction needs an alkin. So let's draw a generic alkin with substituents R one, R two, R three and R four. And let's remember that osos is essential results in a cleavage of the carbon carbon double bond. Number one, we need to use ozone at negative 78 °C. And number two, we are performing a reductive work up with the methyl sulfide to get our products. We basically breaking our double bond and we can simply say that we get two double bonds. That's what we can do. At the beginning, we are just going to throw two double bonds, we're going to add oxygen to each end of the newly formed double bonds, right? And then we have our substitutions R one R two on one end, right? And then R three R four on the other end. That's how we get our two products. So our goal in this problem is to go backwards, we understand that if we remove oxygens and combine our double bonds into one double bond, we get our alk. Now, if we look at the first structure, it will be the structure responsible for the five membered ring, right? So we want to find five carbon atoms that would create such a rank. How do we know that the ring comes from the first structure? Well, essentially we need two carbon groups within the same carbon compound, right? Only if we have two carbon groups within the same structure, then we can form a rank. The second structure only has one carbon group. So it's basically an additional fragment from an additional double bond within the alcan acts. So if we label our carbon atoms, let's label them as 123456789, from right to left, we want to find a total of five carbon atoms between our Carboni groups inclusive. So if we look at the left side, carbon number nine can be bonded to carbon number six using the double bond, but we will have 1234 carbon atoms, right. So it it could form a four member rank. On the other hand, if we consider carbons two and six, we have 12345 carbon atoms. And this is exactly what we need. So we understand that carbons two and six, they will form that five member grain. So we can just draw any five member grain we want. So we have a five membered ring and now let's label those carbon atoms. So we have carbons two, right? And let's also add carbon number six, we understand that there is a double bond between them based on our reaction scheme. And if we go counterclockwise, we get 2345 and six. We also noticed that carbon number two is bonded to the metal groups who are drawing that metal group. And carbon number six has 123 carbon atoms, bonnes. So let's draw 12, three carbon atoms. Let's also add that carbonyl group as well as hydrogen, right? We have that aldehyde. And now this is where we have to think about this reaction. The second product that we are forming that heat zone also has oxygen. And we noticed that we still have that extra oxygen coming from the carbona, meaning there's an additional double bond in alkene X, which can be formed from the two carbona groups. We're just going to remove that oxygen atom, right? So let's go ahead and do that. Simply let's remove that oxygen adam and merge our double bonds. So we're also removing the oxygen atom from the key song product. We are merging the double bonds. And we noticed that at the end of the resultant double bond, we will have two ethyl groups. So we are going to throw one of them and the other, we can eliminate the implicit hydrogen atom. There is no necessity to show it, right. So now we have managed to obtain structure ax, that's our ax. And as the problem suggests, we are performing the hydrogenation reaction, meaning we're adding hydrogen in the presence of, let's say palladium catalyst. We know that in a hydrogenation reaction, if the starting material is an alkene, then we are simply reducing our double bonds, right? We're forming single bonds instead by adding two hydrogen atoms across each double bond, right. So first of all, our five member grain will be reduced. We will not have that double bond within the ring anymore. We can just draw that metal group. And now for our side chain, we have 123456 carbon atoms. OK? And the longest chain. So 123 or five. And now let's draw that sixth carbonatum, right? Let's double check 123456123456, right? And we are also going to add that remaining ethel group pride. So that would be our final product. We can clearly see that we have added two equivalents of hydrogen to reduce the two double bonds. OK. So let's label our final product because thats our final answer, which is nlk. That would be it for today. And thank you for watching.

Ozonolysis of an unknown alkene A gives the products shown. Predict the product that results from hydrogenation of alkene A. [There are multiple answers, but only show the one with the 6-membered ring.]

Key Concepts

Ozonolysis

Hydrogenation

Six-membered ring formation

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