The Alkyl Groups - Video Tutorials & Practice Problems

Alkyl Groups Concept 1

Now, before learning to name more organic compounds, we must first take a look at the names of al keel groups. Now what I kill groups. Well, all kill groups, they're formed by removing an H from an alkane compound. And we're gonna say we name alke groups by using the alkane prefix with YL suffix. So if we take a look here, we're starting out with a five carbon chain. That's an alkane. That means its prefix is pent for five. And since it's an Alcaine and ends with a, so this is pen. Now, here we're gonna remove an H to remove an H from this CH three and it becomes CH two, this bond here with the squiggly just means that this here is connected to some other things, maybe a larger molecule, larger portion somewhere else. OK. So it's acting as a branch. So because it's now removed in H it's no longer an alkane, it becomes an al Kel group and its ending is gonna change from Ain to YL. So this becomes pal pal group. Now, here our Al Kane prefixes are based on the number of carbons and typically when it comes to LK groups, we work within the range of 1 to 6 carbons. Beyond this is very unlikely for it to exist as an LK group. Because again, they're kind of serving as branches. If you have a branch carbon, that's eight carbons long, that means your original molecule is something huge, which you're not gonna see at this level of chemistry. So here if we have one carbon, our prefix is meth. So as an Alke group, it's methyl, two carbons is F as an AL Q group. It's fl three carbons is prop, propel, four carbons is but Butel five carbons is Pent Pentti and then six carbons is Hex Heel. So that's how we name each one of these alk groups. And remember we create an ALK group by removing an H from the original Alkane group and then it's attached to something. Um In this case, we don't know what it is. We just know it's attached to something else.

Alkyl Groups Example 1

So here it says provide names of the AL Q groups below. All right. So these are al Q groups because they're attached to something else which we don't know. So we know they're gonna end with YL. Now their prefix name is based on the number of carbons present. Remember lines connect carbons together. So this one here has 1234 carbons present, the prefix would be but so this would represent a bal alke group for the next one we have. How many carbons? 1234566 carbons means that our prefix is hex. So the al Q group is heel. So this is a heel al Q group.

3 and 4 Carbon Alkyls Concept 2

Now we must learn additional names for our kill groups with three and four carbons. These molecules have structural or constitutional isomers. Remember these are isomers that have the same molecular formula but different connectivities. And we take a look here if we're dealing with a three carbon alke group. So here we have 123 carbons. This would be a prop. But who's to say that the connection is at this end carpet, we have a chance that that connection could be on the middle carbon instead. So here we rearranged our bond and the connection now is on the middle carbon. When this occurs, this group, this alke group now becomes iso propol. OK. So when it's on the end, it's prop. But if it's on the middle carbon, it becomes isopropyl for four carbons, it comes even more complicated. So if we're looking at the first image, we have four carbons, 1234, we know the prefix is, but here if it's at one of the end carbons, it's beautiful. But who's to say that it has to be at that end carpet? And who's to say that the chain has to be a straight chain, if we move to the left, let's say, instead of being at this end carbon or this end carbon, it happens to be on one of the middle ones. In this case, we see it here on this middle carbon. Now, this is called sec beal se because it represents a secondary carbon. This is just a carbon attached to two other carbons. This secondary carbon in blue is connected to 12 other carbons within this Alke group. That's why it's a secondary carbon. Now, who's to say that it's a straight chain, we could rearrange the four carbons in a different order here, we still have four carbons here, but it's just rearranged a little bit different. Instead of being a straight chain, we actually have a branching group here. This one here, if it looks like this, then it is called Iso zero. So in this fashion, it's Isobel. And then finally, in this last one, maybe the four carbons orient themselves in this fashion where this middle carbon here is connected to three of the carbons. And that metal carbon is what's attached to something else. In this case, we call this church. But why is it called Turk Butle? Because that carbon in red is a tertiary carbon. Tertiary carbon means the carbon is attached to three other carbons. If we look that carbon in red is connected to 123 other carbons, that's why it's a tertiary carbon. So again, for three carbon and four carbon alke groups. It can get a little bit tricky because we have different structural slash constitutional isomers that are possible if you have propol, you could also have isopropyl butyl even more. So there's Butyl sec, Butty, Isobel and Tutty. So keep in mind the names that we see here and the way the connections kind of work out when they exist as alke groups. This is key to naming them correctly and key to when we start naming more organic compounds.

3 and 4 Carbon Alkyls Example 2

Here in this example, question it says provided below is a structure of an alkene, identify names of Allah kill groups present in red. All right. So if we take a look here, this is our chain and these are kill groups are the branches coming off of that chain if we take a look at the first one, so it's branching off this branch group here has 123 carbons that are not part of this main chain. Three carbons mean there's one of two possibilities, either propol or isopropyl, it would be propol if the connection to the main chain happened at one of the end carbons. But instead it's happening at the middle carbon, meaning that this alko group is isopropyl. Next, we have this carbon branching off of the main chain. It is just a single carbon. So we know it's an LQ group. So it's YL and one carbon has the prefix of meth. So this would be methyl. Next, we have this chain branching off of the main chain. So this is 123 carbons long, those three carbons, the bonds at one of the ends. So this would be propol and then finally, we have this one branching off which is made up of 12 carbons. We know the ending is YL, two carbons. Its prefix would be F so those two carbons would be ethyl. So our four alkyl groups in this alkane are isopropyl, methyl, propol and ethyl. So those would be our final answers.