Here it says determine the systematic name of the following alkyne. So to do that we're going to employ the following steps. Step one, we're going to find the longest carbon chain which represents our parent chain and assign name according to the prefixes and modifier. Now the parent chain should include a triple bond and have greatest number of carbons or greater number of carbons if a tie between along this chain. Choose chain with more substituents.
Step 2 you would assign name to all the substituents. Alright, so first let's look at what the longest chain could possibly be here. So I need to make sure that the double bond, the triple bond actually is within that longest chain. So we have here what 1234? Yes, there's a carbon here and a carbon here next to the double, next to the triple bond 5. And then we could go 6/7. If we did that, that would give us what that would give us 2 substituents.
But is there another way we could number this? Could we go 123-4567? That is also A7 chain alkyne, southern carbon chain alkyne. But look how many substituents do we have now 1/2 three. This way gives us more substituents, and it also gives us the longest carbon chain as well. So this is the correct way to go. So we're going to say that our longest carbon chain that includes the triple bond and gives us the most substituent would be this way.
Alright. And we've determined who the substituents are. There's this one carbon here which is a methyl, this one carbon here which is also a methyl, and then two carbons here which is ethyl. OK, start numbering the chain from the end closest to the triple bond. Assign location to the first triple bonded carbon. Alright so if I go 1234 to reach the triple bond or go from this end 123 and I get to the triple bond. So this is the way I should number it.
Alright, so we figured out our substituents. We've determined our longest carbon chain that includes the triple bond. Step 4 through 6 is just using the rules that we've employed basically in other topics, namely alkanes with substituents. If you ever watched that video, make sure you go back and take a look, because in those videos we talk about where we have to name the substituents alphabetically and we also have to give numerical locations for them.
Alright, so 7 carbons is heptane. But remember we change the ending from Ain to yin. So here comes have time. The triple bond starts on carbon #3, so three have time. Now we have to give the numerical locations of the substituents and name them alphabetically. E comes before M, so we'd say that this would be 5 Ethel. And then we have methyls on carbons 2 and six, so two, six. Since they're both the same substituent, we use the numerical prefix die methyl dimethyl and then dash 3 Hep time O. The name of this structure will be 5 Ethyl, 26 Dimethyl, 3 Heptai.
