Do the following compounds have the E or the Z

Question

Do the following compounds have the E or the Z configuration?

c. Structural diagram of a compound showing a double bond with bromine and alkyl groups for E/Z configuration analysis.

d. Structural diagram of organic compounds with labels indicating potential E or Z configurations.

Accepted Answer

All right. Hi, everyone. So for this question, let's go ahead and determine whether the molecules in the following list have an E or Z configuration. And here we have two kings. So first and foremost, right, let's go ahead and talk about the difference between E and Z configurations of all keys. And to do that, we have to understand the concept of identifying relative priorities in in a molecule, right, in an. So here, the thing about all keys is that both SP two carbons have two substitutes attached to them. So the idea here is to compare the substituent of each sp two carbon and decide which of each pair is the higher priority. And we do that by looking at their atomic number. So what we do here is we look at the atom directly attaching to the SP two carbon and we look at its atomic number now between two atoms, right, making the connection to the SP two carbon, the higher the atomic number it has, right, the higher priority it's going to be. But sometimes we have a situation where the same exact atom is making the connection to the SP two carbon So from there, I like to call it, you know, breaking the tie because when it comes to a situation where the same atom is connecting to the sp two carbon of the All Keen, there's kind of a tie there, right? Because they would have the same atomic number. So from there, you would have to consider what else each respective atom is attached to and see where the difference lies, right? And therefore what breaks the tie, so to speak. So now let's apply this to both Keen A here and Keen B now for both all keys, I'm going to go ahead and label my SP two carbons, one and two, right? So for a KA, I have carbon one on the left side here and carbon two is going to be the SP two carbon on the right side of the al key. Now attaching to carbon one, I have a carbon which has an atomic number of six and I have the oxygen of my hydroxy group which has an atomic number of eight. So here because oxygen has a higher atomic number than carbon, it's going to be the higher priority group of carbon one here. So let's keep that in mind and I'm going to circle it for ease of reference. And now let's look at carbon two, right. Carbon two is connecting or connected to hydrogen which has an atomic number of one and carbon which has an atomic number six. Now here, carbon is going to be the higher priority group of carbon two because it has a higher atomic number than hydrogen. So here I could circle that better. There we go. So here look what's happening, right? For ease of reference, I circled the higher priority group on both sides of the all keen and I've come to notice that they are on opposite sides of the all keen itself. So because of that, right, OK. A here is said to be in the E configuration because my highest priority groups are on opposite sides of the all keen itself. So now let's look at all can be. And again, for alkene B, I'm going to say that carbon one of the alkene is on the left side and carbon two of the alkene is on the right side. So for carbon one, we have the same substituent as carbon one of all K A, right, we have one carbon and one oxygen in the hydroxy group, which means that oxygen once again, is going to have the higher priority because oxygen has a higher atomic number than carbon. But look what's different for carbon two. For carbon two, the atom connecting to this sp two carbon. Here is carbon, both have an atomic number of six. So this is what I meant when I was talking about there being a tie, right? Carbon has the same atomic number. So at this point, we cannot determine the relative priority So from here, we have to kind of branch out and see what else these carbons are connecting too to see what can break the tie. No, we have an EO group and a carboxylic acid group. And the EO group means that the first carbon here is connecting to another carbon which has an atomic number of six. But in the carboxylic acid, my carbon is connecting to oxygen which has an atomic number of eight. So here oxygen is breaking the tie because it has the higher atomic number than the other carbon of the ethyl group. So here I'm circling the carboxylic acid group. And what I'll notice is that the carboxylic acid group and the hydroxy group are connecting to the same side of the all Keen, which means that they're going to be in the Z configuration by contrast and there you have it. So all key A is in the E configuration because the highest priority groups are on opposite sides and all Keen B is in the Z configuration because the highest priority groups are on the same side. So with that being said, thank you so much for watching and I hope you found this helpful.

Do the following compounds have the E or the Z configuration?
c.
d.

Key Concepts

E/Z Configuration

Cahn-Ingold-Prelog Priority Rules

Geometric Isomerism

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