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Current time:0:00Total duration:8:11

Video transcript

we've got a few more molecular structures to name so let's look at this first one right here so the first thing you always want to do is identify the longest chain so if we start over here we have 1 2 3 4 5 6 7 8 9 10 11 12 13 carbons looks pretty long now what if we start over here this looks like it could also be a long chain 1 2 3 4 5 6 7 8 9 10 11 12 13 so we have two different chains depending on wonder whether we want to go up here or whether we go over here that have a length of 13 so you're probably asking which chain do you choose and you should always if we have two chains of equal length and there the longest chains you pick the one that will have more branches or more alkyl groups on it so this group right here if we pick this kind of from here to here as our chain we only have one group on it that group up there if we pick this chain starting over here and then going to over here we have two groups on it we would have this group over here and then we would have and then we would have this group this group over here so this is the better chain to use because it has more groups on it it has more groups but the groups are smaller and simpler so let's start counting and the direction we want to count we always want to start on the side of the chain where we're going to encounter something first and everything is closer to this end of the chain so we'll start counting here we'll start counting here 1 2 3 4 5 6 7 8 9 10 11 12 13 so we have 13 carbons on our main chain let me draw our main chain so our main chain is this thing in orange I'm drawing right here that is our main chain like that 13 it's 3 & 10 the prefix is tri deck and it's tri decane because we have all single bonds here so just try decane try decane is the main chain and then we have two groups over here this one in green this only has one carbon branching off of the main chain so it's prefix will be meth then it'll be a methyl group so that is methyl that is a methyl group right there and then this one down here we have one two three carbons the prefix is pro so this is a propyl group this is a propyl group Pro pill group and this is the methyl is sitting on the three carbon the methyl is sitting on the three carbon of our main chain and the propyl group is sitting on the four carbon one two three four now when we figure out what order to list them in when we actually write out the name em we just do it in alphabetical order M comes before P so we write 3 methyl before four propyl so the entire compound here is or the entire molecule is three three methyl three methyl four propyl four propyl tri decane four propyl tri decane tri decane and this is actually all going to be one word if you don't use dash to separate when you have numbers but if you have a word file bar where it just becomes purple tri decane so three methyl four propyl tri decking and we're done now let's do this one down here now this one seems a little bit more complex so the first thing to see is what is the largest chain or the largest ring that we have in our structure and the two candidates we have this chain over here this has one two three four five six seven carbons let's see how many carbons our ring has our ring our ring has one two three four five six seven eight nine carbons so the ring is the largest I guess you could say core structure in this molecule so that will be our that will that will be our core structure and so we have nine carbons let me highlight it so the ring ring is this right here has nine carbons the prefix for nine is none it's all single bonds so it's nonane and it isn't a cycle it's a ring so it's cyclone on Ain so this part right here that part right there is cyclone on Ain cyclo nonane and then we have several things that branch off of the cyclone on n so let's look at it one at a time and then we'll think about how we're going to number them on the ring so we looked already at this at this chain that has seven carbons one two three four we do that other blood like the other blue better one two three four five six seven so that is a Heptulla group kept till group now this over here let's see what we're dealing with we have one two three carbons so that is just a standard propyl group so this is just a standard propyl group and then here here we have we have one two three four carbons so we could say this is a butyl group but this isn't just any butyl group if we use the common naming the carbon we immediately touch on or that we immediately get to when we go off of our main ring that branches off into three other carbons so this is tert tert four three so this is and the tert is usually written in italics it's hard to differentiate that when you see it when you see it I'll write it in I'll write it in cursive tert this is tert this is a tert-butyl group now the next question is how do we specify where these different groups sit on this main ring now if you just had one if you just said one group you wouldn't have to specify but when you have more than one what you actually do is you figure out which one would be alphabetically first and that would be number one now we have an H and Heptulla P and propyl and tert-butyl you might say well do I use the T or do I use the B and this is just the convention you use the B if you have sex beetle or tert-butyl you ignore the Tet the sec or the tert if this was an isobutyl or isopropyl you actually would use the I so it's a little bit you I guess the best way to think about is there's a dash here so you can kind of ignore it but if this was isobutyl it would all be one word so you would consider the I so in this situation we would consider the B & B comes before P or an H so that is where we will start numbering one and then to figure out which direction to keep numbering in we just go in the direction where we're likely to encounter the first or where we will encounter the first chain the first side chain so we'll go in this direction because we get right to the propyl group one two three four five six seven eight nine so this compound we're going to start with the alphabetically first side chain so it's one tert-butyl it's one tert let me write that in cursive let me get some more space here so it is one I'll write this in cursive tert tert-butyl one tert-butyl then the next one alphabetically is the hep total group that's H for hep dose so then it is v hepta l-- v hep dough and then we have the propyl and then it is two propyl two propyl two propyl and then finally cyclone on a cyclone on a cyclo nonane and we're done