The 2004 IUPAC names for alkyl groups are derived from the alkane having the same carbon chain as the alkyl group. The -e ending of that alkane is replaced by - yl, and the chain is numbered from the end that gives the carbon at the point of attachment its lower number. This number immediately precedes the - yl ending and is bracketed by hyphens.
Name the C4H9 alkyl groups according to this system.
Hey guys. So, for this question it wants us to name the C4H9 alkyl groups that we can actually draw in and name, so it gave us these two that are five carbon chains that it wants us to base our naming off of and they give you some rules to follow, so let's get started by showing that we can draw four carbons like this, and draw this diagonal. So, 1, 2, 3, 4 and I have the branch come off right here, okay? Or, we can also represent this being a CH2, CH2, CH2 and CH3 then we have it coming off right here, we're going to name this five giving the point of attachment, the lowest number. So, here we're going to start labeling it as 1, 2, 3 and 4 for our carbon groups, okay? And we're name this a little bit different because it's actually an alkyl group and it's gonna be different because we know it's going to be butane, right? You would expect if I just gave you two label the bond line structure in black, we would call it butane, well remember is an alkyl group and it want us to identify where it is actually coming off of, so we're going to take off the ending and after the end what we're going to do is we're going to take up the E and make it wide out and we actually going to indicate the point of attachment. So, right here it looks like the point of attachment at our carbon number one, okay? So we add on to this one and then you know, so butan-1 yl. Now, let's move on to any other way we can draw our point of attachment. Notice that right now it looks like it's coming off of this one carbon, but you can have it coming off in the middle of our structure. So, in order to draw that, say we drew another carbon chain like this then on the point of attachment came over here. So again, we would have CH3, we'd have CH2, we'd have CH and of course CH3. Now, right? So, where is the point of attachment on this structure that I drew? Well, the point of attachment is now going to come off of say a more central carbon like this, so what do you think we're going to call this structure? it still the longest, we're still going to label it like this 1, 2, 3, 4 and notice we wanted to give that point of attachment the lower number, so that's why we went from the right. So, here we're going to call it a butan-2, okay? So that indicates that our point of attachment for our alkyl group in opposition two.
Now, can you think of any other ones that we can draw that would maybe be a little bit more branched? Well, yeah, right? Because now let's say we drew our structure that look like this this, CH3, CH, CH2 and CH3 coming off of this carbon. So, something like this and we have a point of attachment B over here, okay? So here what we can draw is we can represent it like this, we have a CH2, CH, CH3 like that and the point of attachment is right here. Well, we're going to get that point attachment at the lower number, so we can actually give it a 1 come here, 2 and give this 3, so the actual name for this would become how many and how long is the chain now? 2, so this would be propan that point of attachment is at position 1. So, 1 yl, what are we missing anything? Well, here we actually have one of our groups being a substituent, right? So we need to give that substituent an actual name, so we're going to call this them in total 2-methyl, right? And then we're going to give it propan 1 yl, okay? propan, that should be a 1 and then yl to indicate the position. Now, if you think of any other ones, well, we actually make this an extremely branched structure and what we can do is, let's say we do it up here at the top and what we give it and we have a CH3 off coming that way CH coming there, CH3 there and on the point of attachments is like this, okay? So this, remember, is a carbon group. Now, this can also be represented like this, so let's move our C4H9 over here, expand that and let's draw this another representation where we have CH3, we have CH3 and we have CH3 and in the middle we would have a just a carbon because it's attached right here, okay? So now how would we name this structure? we need to give that point attached of the lowest number and we want to get the longest carbon chain possible, so we label it as 1, 2 and 3 because we could just label this as 1 and this is 2, right? Because we would have had the longest chain possible. So, here what we're going to call this structure is now we have substituent here, okay? So we can say that this is going to be a three carbon chain propan but now it's 2, right? And now we didn't need to indicate that we have a methyl, so it's going to be 2-methyl, okay? And right now we could just show that we have one right here, we have one right here, we have another right here and then our last one that we can draw is actually right here, okay? So these are the alkyl groups that we can draw that are 4 carbons long and that have 9 hydrogens on them. Alright, hopefully this makes sense on how we name them by indicating where that point of attachment was.