For the following terpenes, identify the isoprene units. In cr...

Question

For the following terpenes, identify the isoprene units. In cross-linked or ring-containing terpenes, linkages can be formed between more than just C₁ and C₄ of isoprene.

(d)

Accepted Answer

Hi, everyone and welcome. Our next question says, determine the isoprene units in the following terpin slash terpenoid linkages can be formed between more than just C one and C four of iso isoprene. When the Turpin or terpenoid is ring containing. So our Turpin or turid here is called food Jone. It's a very weird structure here. Kind of looks like an arrow. We have a carbonell group, we have a ring and we could see several branches sticking out. So let's recall that we were trying to identify isoprene units. Our basic structure there is a four carbon structure where we have a methyl group on carbon two. And then we see a double bond from carbon one to carbon two and from carbon three to carbon four. And these groups can link together multiple times with the most common method of doing that being between carbon one and carbon four label these and we see that the methyl branch is carbon two. It's going to be important for identifying our eye supreme units. Sometimes these can link in other ways, they can form it from C one to C one or C four to C four. But this is the most common C four to C one linkage. So let's go back to our molecule here and we need to identify the isoprene units. So when we do that, we first ignore the functional groups and then we look at our carbon skeleton for that characteristic methyl branch. Once we find it, we label the methyl branch as carbon five and then it's attached carbon as carbon two. So we label carbon five and carbon two. And then once they're labeled, we go and label carbons 12 and sorry, 13 and four. Now, no, we had this little note here telling us that when we have this ring structure, we can end up with more linkages than just the one C one C four linkage. So as I look at my three gen molecule, I see two metal branches that jump out at me right away. So I have this carbon carbon group of this communal group on the left and it has two links on the top. There's a link to a carbon that has a methyl branch. So I'm going to label the carbon with the branch is carbon two and then carbon five is the methyl carbon. So when I do that, I'm going to label carbon one as the carbon carbon. And as I continue around in my ring, I now have one and two labeled. So I just label the next two carbons three and four. And that makes carbon four sort of the tip of this arrowhead shape that our ring takes on. Now, I want to look for my other isoprene unit. Note that I'm not worrying about possible double bonds here with this conjugated double bond structure, the original is supreme. They can, those double bonds, the electrons can move around. And we're just looking for that basic structure with the methyl branch. So I've gone to sort of the tip of this arrowhead. And as I move around carbon four is bonded to carbon five, carbon five has two bonds, it's bonded to carbon three, sort of cutting across the arrowhead and then it's has bonded to another carbon with two methyl groups. So kind of one looks like an isopropyl group coming off of carbon five. So right there in the isopropyl group, I have a methyl branch. So if I label the end of one of those as carbon five, the carbon is attached to must be carbon two, the other methyl group would then be carbon one and then carbon three will be that carbon in the ring. Notice that it has this bond across the ring to the other carbon three. So that's an example of those other linkages we saw. And then finally, carbon four going to the left in the ring. So I'm going to use a blue highlighting to label my first isoprene unit. So that's the one starting with the carbon carbon and then ending with the sort of tip of the arrowhead there. That's ice cream unit number one. Then I'll use yellow highlighting for our supreme number. Unit number two. And when I look for the C one to C four link, I expect to see between the two, I have to go all the way back to carbon one of the ice cream unit I just labeled and it is connected to carbon four of the other ice cream unit within the ring for that bottom part of this arrowhead sheet. And then I can go all the way to carbon one which is out on that is isopropyl branch. We mentioned we can just highlight the whole skeleton of those molecules in their respective colors. And we do see examples of how there can be more than just the expected C one C four linkage. So we'll say additional linkages and we have that link between the two carbon threes that go to Kasar ring. So carbon three to carbon three and then we see another linkage at the tip of my arrowhead. So within the ring between carbon four and carbon three. So there are additional linkages that are possible here with this ring structure. And we see that we've identified our two isoprene units for a three J molecule. You in the next video.

For the following terpenes, identify the isoprene units. In cross-linked or ring-containing terpenes, linkages can be formed between more than just C₁ and C₄ of isoprene.
(d)

Key Concepts

Isoprene Unit

Terpene Structure

Cross-Linking in Terpenes

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