If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content
Current time:0:00Total duration:7:43

Video transcript

let's see if we can name this guy right over here and so like always we always want to look for the longest carbon chain or the longest carbon cycle and I think it's pretty obvious from this picture that we have a very long carbon cycle here that we can start or we can just look at this we have one two three four five six seven eight carbons in a cycle right over here and so we can call this backbone which is the backbone of our molecule right over here this is cyclooctane cyclo cyclo octane it's an octane in a cycle it's an alkane because it's all single bonds right over here so that is cyclooctane now let's think about the different groups that are attached to this to this backbone right over here so first we can look at this one right over here and we could ask ourselves well how many carbons are there how many carbons well there's one two three four carbons that are attached to the backbones so our prefix phone we're dealing with four carbons is butte and it is in a cycle so this is a cyclo beautiful beauty o butyl and we also have another cyclo butyl right over here so this is another cyclo butadiene beyou I'm spelling it cyclo beauty group now let's think about let's think about this one right over here how many carbons are there we have one two three carbons so our prefix when we're dealing with three carbons is proq and they're in a cycle as well so this is a cyclopropane propyl group and now we can jump over to do these two groups right over here we see that these are clearly the same groups let's count let's count the number of carbons they have well we have one two three four carbons so if we're dealing with four carbons we would think about the prefix Butte but this isn't in a cycle and it's not in just a straight chain it has this Y shape and so the common name when we end up with this Y shape when we're attached down here and then that's we're attached to one carbon here and that's attached to kind of this this this this this carbon right over here this isn't attached to these other two this is an isobutyl group which we've seen multiple times before ISO butyl isobutyl group and of course this one is an isobutyl group as well so these are both these are both ISO butyl groups now the next thing we need to think about is how we can number it we want to go back to our main carbon chain which in this case is a cycle and think about how we want a number and the convention is is to start numbering at the thing that is first in alphabetical order and we consider alphabetical order we think even the Sein cyclo and we think of the I & isobutyl if this was dirt or SEC you wouldn't think about the T or the s and sec beetle or tert-butyl but for isobutyl you do consider the i for the cyclos you consider the c and so when you look at it that way all of the C's come before the eyes and then amongst the C's these all have cyclos but the cyclo beautiful propyl or cyclooctane B comes before P or O so the thing that is first alphabetically are both of these both of these cyclobutane start numbering we can start numbering at where either of them attached to the main carbon backbone but we have to we have to or what those are I guess we should say those are both options but we want a number from the one that is going to give us the total lowest numbering so let's think about that a little bit so we could say let's number from here let's make this the one carbon and so that we hit something else as soon as possible because remember we're trying to minimize the numbers here we might want to go clockwise so we hit a 2 right over here 3 4 5 6 7 so in this situation where do we hit interesting things we hit interesting things at the one at the 2 or where do we have groups attach the chain 1 to 4 four six and seven so that's one option we'll have things groups attach it one two four six and seven if we start right over there and if we were to go clockwise our other option one two four six seven our other option is to start it let me erase those our other option is to start at this other cyclobutadiene whole group here on the left let me erase these so I don't mess up the diagram too much the other option is to start here make this the one number this is one and then we would also go clockwise to hit those cyclopropyl as soon as quickly is to hit something else as soon as possible so two three four five six seven so now where are we hitting interesting things we have groups at the one carbon the two carbon the four carbon the five carbon and the seven carbon and the seven carbon so actually this second numbering is preferable both of them have something at the 1 the 2 the 4 and the 7 but the second one has something at a 5 while the first one had something at a 6 so we would actually want to do this numbering right over here and this is the numbering that we now have on our that we have that we have now listed right over here let's now write what the name of this molecule actually is so once again we start first in alphabetical order so we're going to start with the cyclo butane and one at the four carbon so we could say 1 comma 4 and since there are 2 cyclobutadiene 1 4 die cyclo butane what comes next in alphabetical order is the cyclopropyl that comes before isobutyl C comes before I that's at the 2 carbon so then we can say 2 2 cyclo propyl 2 cyclo propo and now we can get to the two isobutyl x' so there's an isobutyl at the five carbon and at the seven carbon so we can say we can say five seven and since there's two of them we'd say dye isobutyl five seven dye dye isobutyl so dye I so beYOU dye isobutyl and then we just give the name of the backbone we've tackled we've done the beutel's the dye cyclobutadiene the two isobutyl x' and now we just write cyclooctane cyclo cyclooctane cyclooctane and we are done we have named successfully named the molecule and this was kind of fun it's like a it's like a secret code or something you wouldn't expect doing naming organic molecules to be I think quite so satisfying but what it is