Naming Alkynes - Video Tutorials & Practice Problems
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Rules for Naming Alkynes Concept 1
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Now recall that an alky possesses a carbon, carbon triple bond. And we're going to say here that the set of rules for naming alkanes are very similar to the ones for alkenes here. Though, the modifier is we're going to change the ending of aim coming from an Alkane to Yin because we're dealing with an al Kine. Now, a good thing here is that all kinds because we have a triple bond, they do not possess cysts or trans isomers here. In terms of our naming convention, we'd still have to give the location, the numerical location of substituents. We'd have to give the location of our triple bond in our structure. And again, we'd have our modifier where we change the ending from Ain to Yen. So keep that in mind when we start naming different types of all kinds.
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Naming Alkynes Example 1
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4m
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Here, it says, determine the systematic name of the following alky. So to do that, we're gonna 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 I tie between along his chain, choose chain with more substituents. Step two, you would assign a name to all the substituents. All right. So first, let's look at what the longest chain could possibly be here. So I need to make sure that the double bond though 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 um next to the triple bond uh five. And then we could go 67. If we did that, that would give us what that would give us two substituents. But is there another way we could number this, could we go 1234567 that is also a seven chain uh alk kind south carbon chain alky. But look how many substituents do we have? Now? 123, 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 gonna say that our longest carbon chain that includes the triple bond and gives us the most substituent would be this way. All right. 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, assigned location to the first triple bonded carbon. All right. 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. All right. So we've figured out our substituents, we've determined our longest carbon chain that includes a triple bond step four through six is just using the rules that we've employed basically in other topics, namely our cans 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. All right. So seven carbons is hap but remember we changed the ending from A to Yin. So here comes have time, the triple bond starts on carer number three. 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 five apple and then we have methyl on carbons two and six. So two comma six. Since they're both the same substituent, we used the numerical um prefix dye methyl dime methyl and then dash three hap time. So the name of this structure will be five ethyl, 26 dimethyl three hap time.
