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Current time:0:00Total duration:10:26

Video transcript

I've pre-drawn some molecules here let's see if we can use what we know to name them so what do we have this first molecule right here I have a bunch of rings this is a one two three four five six carbon ring these are each four carbon rings one two three four one two three four so the largest ring is essentially going to be our backbone so it's going to be this six carbon ring right here one two three four five six carbons so that is a cyclohexane cyclo hexane all double bonds that's what we get the Ain six carbons hex it's in a cycle cyclo and then we have two of these four carbon rings so four carbons we dealing with the prefix beaut beaut four four and we've got to them so both of these are butyl groups both of these are butyl groups both of these are butyl groups but they're in a cycle so they're actually cyclo butadiene cyclo butadiene right there and we only had one thing attached to it you wouldn't have to number when you have two things you start numbering at one of them so let's say we start numbering here and you go in the direction so that the next group has the lowest number so in this case you want to go in the counterclockwise direction if we went this way it'd be one two three four five this guy would be a five if we go in the counterclockwise it'd be one two three this guy will only be a three so this right here we have to cyclobutadiene all it is die die cyclo butadiene they are at d1 and three position so the one and three position I have two cyclo butane my cyclohexane I guess you could call it main ring let's try this one right here so I have a five carbon ring one two three four five right there and then I have a D one two three four five six carbon ring right there so this is going to be the main ring that is a cyclohexane cyclo hexane has six carbons on them in a cycle all single bonds and attached to that I have a cyclo pen till group yl for the group so this is a this is a cyclo penta l' until group on it we don't have to we don't have to number it because it's only one group attached to the main ring if there was another group we would have to number it like we did up here so this is cyclopentyl that's this part right here cyclopentyl attached to cyclohexane cyclopentyl cyclohexane now let's try this one over here so the first thing we want to do this isn't there's no cycles here but we have to identify the longest chain to do that let's just count it out it could be one two three four five six seven it's not the longest chain maybe it's one two three four five six seven eight that looks like the longest chain so let's make that the longest chain let's make that the longest chain right over there make that the longest chain we want to start numbering in the direction so we encounter the first attached groups first so we do want to start numbering down here because we have groups attached right on the two carbon if we started over here we would have to go pretty far until something's attached so we go one two three four five six seven eight so we know we're dealing with an octane all single bonds it's not a cyclooctane it's not in a cycle so we're know we're dealing with an octane we know we're dealing with an octane and now we just have to add the groups to it so what do we have here what do we have here this right here is just one carbon attached to the main chain this is another carbon attached to the main chain so both of these right here are ethics our methyl groups method is for one carbon those are methyl groups now we have if you look at all of them these are the only methyl groups these two up here aren't methyl group so we have two methyl groups on our entire chain so it's going to be dye methyl and they're both of the methyl groups are at our two positions so this is going to be two to dimethyl this part right here is too - that right there is - to dimethyl we're going to decide what order to write it in what we we figure out what these are called because it has to be in alphabetical order so this is - to dimethyl the whole chain is an octane what are these over here well these how many carbons how many carbons do we have here 1 2 3 they actually look the same we have 1 2 3 here we have 1 2 3 there so these are both propyl group these are both propyl groups propyl groups and if we deal with common names this is kind of that Y shape you could call it sec propyl because this carbon right here that's attached to the main chain is attached to two other carbons for the more common one because this part forms this Y shape is isopropyl it's isopropyl and we have two isopropyl groups these are both isopropyl so we would want to call this let me actually so we have two isopropyl groups so we would have died isopropyl let me write this die ISO propyl die isopropyl and they're occurring at the four and five positions - isopropyl zat four and five so this is four and five diisopropyl that's that group and that group right there are accounted for with this now we have to just figure out the order that we write it in you ignore the die or the try out front and you just look at them in alphabetical order so we have an eye for isopropyl we have an M for methyl let's write the isopropyl first and I've actually seen some people wanted to go for the P but I'll the main thing I ignore is just to die or the Tri in front of the isopropyl you shouldn't involve that but everything after that you do involve so I'll write the isopropyl I'll write the isopropyl first I comes before M so this is going to be if we were to write the whole thing this is going to be for five die isopropyl isopropyl die ISO propyl - to dimethyl - - actually this should be a comma here 4 comma 5 4 comma 5 diisopropyl 2 comma 2 dimethyl die methyl octane octane octane and we're done but this was just the common name you might remember that you know when we do with ISO or sack or tert-butyl or propyl or whatever that's the common name if we want the systematic name we can look at the we can start at where we are attached to the main chain and view that is 1 and then make the longest chain with that as 1 and so you could say that we have a chain there and this would be both of these cases so this is one two carbons two carbons we're dealing with an ethyl we're dealing with an ethyl and on the first carbon you have a methyl attached to it so you could also call each of these groups a 1:1 methyl ethyl instead of an isopropyl so you could either say isopropyl for each of these groups or you could call each of them a methyl ethyl if you do systematic naming now you can't well you don't we have two of these one methyl ethyl groups just like we had two isopropyl groups if you're using common naming you can say diisopropyl to say you have two of these groups when you're using systematic naming you don't say die one methyl ethyl although that would probably would get the point across you use this so this is since we have two of them instead of writing instead of writing die you write Biss you write this one methyl ethyl that means you have two of these things right there and it's still n the four in the four and the five position and if you look at it in alphabetical order now methyl ethyl comes after methyl right so the order will now change so now if you want to write it with systematic naming it would be written as two to dimethyl dimethyl that's these two guys two to dimethyl ethyl and then you would write this guy so the order changed for the two groups just based on how they're named this this and then over here you have two one methyl ethyl groups I know it's confusing when you just break it down it actually makes a reasonable amount of sense one do you have two of these methyl ethyl groups oh sorry I forgot where they're located so we have them at the four and five position so in the four and five position four and five position we have two so this we have two this one methyl ethyl groups methyl ethyl I know it's a little daunting now but it all makes sense when you break it down at men methyl ethyl groups and then we can just add the octane at the end octane let me scroll over to the right a little bit okkk octane and we're done now this might seem more confusing but when you break it down it makes sense you have octane as the backbone we have two methyls they're both sitting on the two positions so you have two methyls sitting on the two position and then you have two one methyl ethyl group sitting at the 4 & 5 position so in the 4 & 5 position one methyl ethyl one methyl ethyl you have an ethyl and in the one position you have a methyl so that's all it's saying or you another way to think about it it just in case this doesn't confuse you enough you could call it that or you could say 4 comma 5 dye isopropyl these two things are the same thing common naming systematic hopefully you found that useful