Of all the possible cyclooctanes that have one chloro substitu...

Question

Of all the possible cyclooctanes that have one chloro substituent and one methyl substituent, which ones do not have any asymmetric centers?

Accepted Answer

Hey, everyone. And welcome back, Which of the cyclohexane isomers containing one bromo group and one chloro substituent do not possess any asymmetric centers. So now to solve this problem, we are going to consider cyclohexane because that's what the problem suggests. So we are going to draw our six membered ring. And we first of all, once you consider what are the possible isomers. So let's suppose that we are just going to add bromine to the first position. And then we are going to consider the possibilities of adding our remaining Chloro substituent. So first of all, for the first structure, we can just add both of them at the same carbon atoms so that we have bromine and chlorine on the same carbon atom. Now, for the second visibility, we can once again add bromine to position number one. And now we are just going to move chlorine to position two, similarly going clockwise. If we keep the position of bromine fixed, We are going to add it that carbon one and then chlorine at carbon three. And finally, we can have another possibility, we can add bromine to position one chlorine to position four. So far those are the only possibilities because if we keep shifting chlorine clockwise, that would just be a reflection of the previous structure. Meaning we are done. Now thinking about these structures, we want to identify those that do not possess any asymmetric centers. So now when we think about the first structure, we can say that this works for us if the carbon atom that has bromo substi and Chloro substituent is not chiral because it does not have four different substitutions. Basically speaking, there is a line of symmetry which is a vertical line. And on the left, as well as on the right side, we have two equivalent kiel groups from the ring bonded to that carbon. So that means the first structure Does not possess any asymmetric centers. And that's one bromo one Chloro Cyclohexane. That's our first answer. Now, we are going to consider the second structure bromo and Chloro substitutions are on adjacent carbon atoms. So we can actually have stereo centers specifically, there's no line of symmetry passing through our compound and that's sufficient to understand. So if we think about the first carbon atom, it has four different substituent, it has a bromo substituent, it has ach two on the left C H C L on the right and then it has hyen bonded to it. So we have four different substations for the first carbon atom. And that's sufficient for us, even though we have four different substations for the adjacent carbon atom, that's already enough to understand that. Or one carbon atom already has four different substituent. So it will be asymmetric in one of the isomers. So we can say that the second structure does not correspond to our answer. Similarly, for the third structure, if we consider carbon number one, It has four different substitutions bromine C two. Or basically, if we are more accurate, that would be C H two C H two on the left. On the right, we have C H two C H C L which is our difference because the branch on the right is different than the one on the left. We understand that the ring gives us two different substitutions as well as our implicit hyen atom. So that means the third structure already has an asymmetric center and you can conclude the same for chlorine. Now, for the final one, if you carefully analyze it, there is a vertical line of symmetry passing through our compound and it will not have asymmetric centers. And that's because when we think about the first carbon atom, It has bromo substituent, it has an implicit hygiene and it has two equivalent C2 S H two C H C L groups if we go from each side. And since that symmetry, we can understand that the first carbon atom does not have any asymmetric centers. It's asymmetric, it's in other words, it's not chiral, right? Because it does not have four different substitutions. And similarly, you will see the same thing if you consider position four, it has Chloro substituent hydrogen and then two equivalent kiel groups. Z's the line of symmetry. That means the fourth structure works for us. And we just want to give it a name. So that would be one bromo, right? We want to arrange our substitutions alphabetically For Chloro because we have our chloro substituent at position four Cyclohexane. That would be it. We can conclude that one, bromo, one Chloro Cyclohexane and one bromo, four Chloro Cyclohexane. These two structures do not possess any asymmetric centers. We have labeled our final answer in a green box. And based on our answer, we can conclude that there are these two structures that correspond to our answer. Thank you for watching. And I hope to see you in the next video.

Of all the possible cyclooctanes that have one chloro substituent and one methyl substituent, which ones do not have any asymmetric centers?

Key Concepts

Cyclooctane Structure

Chirality and Asymmetric Centers

Substituent Effects on Symmetry

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