Rank the following compounds from most stable to least stable:...

Question

Rank the following compounds from most stable to least stable:

trans-3-hexene, cis-3-hexene, cis-2,5-dimethyl-3-hexene, (Z)-3,4-dimethyl-3-hexene

Accepted Answer

Hey, everyone. And welcome back to another video rank the following substances in order of increasing stability, S five Z 36 ethyl E Z 56 dimethyl S five in and trans five de Let's start by simply drawing these structures and we may notice that they are all Alkins, right? We have a suffix E for each of them starting with CS five death scene. We're going to draw a double bond to begin with, right? Because we want to draw ac structure and when we have our double bond, which starts at carbon number five, we understand that that scene means 10 carbon atoms in the parent. So if it starts at carbon number five, we need to add four more carbon atoms on the left. So that'll be one, two, 34, right? And in addition to that, if we count the number of carbon atoms, we have, we have six. So we need to add four more on the right as the problem suggests, that's a cyst structure. That's why we have drawn the al groups on the same side of the double bond. Now, for the next one, we have t for in. And once again, we're going to draw our double bond in states that the double bond starts at carbon number four, right. So that means we need to add three more carbon atoms on the left, 123 and implies that we have a total of eight carbon atoms. So we have 12345, right? We need three more. And the problem states is Z. So Z similarly to c means that the alka substitutions will be on the same side. So we're going to add three more carbon atoms, right? So we have 12345678, well done. Now at positions three and six, we have two ethyl groups. So if we count our carbon atoms, 123 at position number three, we're going to add one ethyl group and at position six, that'd be 456, we're going to add another eyl group well done. Now for the next one, we once again have five in, right. So similarly to the previous one, we're going to use the structure of the scene at with a double bond at carbon number five. And now it says that we have 56 dimethyl. So at carbon number five and six, we have two metal groups. The configuration is Z which means that the highest priority groups are on the same side of the double bond and those are just longer alki chains. So it makes sense if we place two metal groups below the double bond, that will, that will give us a Z configuration, finally, we have trans five. And if we remember the first structure, it was c so to draw its transversion, we just want to change the way we have drawn our kill group. So the two al kill groups must be on opposite sides of the double bond. So we have 12345, right? The double bond starts as carbon 56789, 10, we have a total of 10 carbon atoms trans arrangement means that the Q groups are on opposite sides of the double bond. OK. So now let's actually enumerate them. So we remember which is which let's suppose that the first one is number one, then we have number two, number three, number four. And we are just going to add these labels to our structures. OK. Now, what we're going to do is just remember the alkin stability and the two aspects that are important for us, number one is the substitution pattern. That means the more substituted our alkins are the more stable they become. And number two STAIC strain, we want to minimize our STAIC strain to achieve stability. In other words, we want to make sure that if the two alki groups are adjacent to each other on the same side of the double bond, we don't want them to be bulky because otherwise they are experiencing significant STAIC strain or STAIC hindrance as well as electronic interactions. So taking into account these aspects, first of all, let's take care of the substitution pattern for the first structure, it's di substituted because there are two alki groups. For the second one, it's also di substituted because we have two alki groups for the third one, it's that trust substituted because we see four groups and for the final one, it's th substituted. So we can state that the third structure will be the most stable because it's the most substituted al. So let's write it down, we can say most stable. Now, the other three structures are all di substituted structures. So let's think about the STAIC strain. First, let's recall that trans alkins are more stable than si right. And basically, that's because we have our groups as far as possible from each other. So they are not experiencing STAIC strain as well as electronic interactions. So if we compare structures one and four, we have C and trans would be less stable and trace would be more stable. So we know that structure four is more stable than structure one. But what about structure to not only it exists but compared to structure number one, the alky groups are branched, right. So we can say that there's a higher STAIC strain compared to the first structure where the alky groups are straight alky groups. In structure two, we have our branched alky groups. So apparently they're closer to, to each other and the STAIC strain increases. So that means structure number two would be the least stable, followed by the version of five death scene and then trans version of five death scene. Finally, we will have our Tetras substituted King, knowing this information, we are ready to conclude our findings. According to our findings, we can now rank our Alkins in terms of increasing order of stability starting with Z 36 ethyl A four in which experiences STAIC strain and is th substituted, followed by CS five which experiences STAIC strain, but the lower C strain due to straight alky chains, but also being dis substituted. Then we have trans five which is still di substituted, but it's trans and trans alkins are more stable than C. And finally, we have our substituted the most stable alkin which is Z 56 dimethyl D five in that will be our trend. Thank you for watching and I hope to see you in the next video.

Rank the following compounds from most stable to least stable:
trans-3-hexene, cis-3-hexene, cis-2,5-dimethyl-3-hexene, (Z)-3,4-dimethyl-3-hexene

Key Concepts

Stability of Alkenes

Geometric Isomerism

Substituent Effects on Alkene Stability

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