all right let's go on to the details of the naming structure and in the general sense there's going to be two parts of a an organic nomenclature the first one is going to be the first name and the last name the last name is going to be the backbone of your entire structure and that's going to be the longest carbon chain that you have and the first name would be whatever side change that is attached to that particular molecule so for example if i were to have a structure that looked like this the longest carbon chain in this case would be this one so that's going to be my backbone or it's going to be the last name and this one here is side chains because it's going to be a lot shorter and it's attached to this longer backbone right so by the way the name of this particular molecule is going to be two methyl pentane all right so that's just going to be the two parts of the name of an organic molecule and we're going to discuss in terms of why is it two instead of four in just a little bit so what else well we also have a suffix or the ending such as an alkane alkene alkyne uh all amine and so on and that's just kind of a different functional group that is attached to your molecule so for example if i were to have um one butene it would look something like this right so we have butene butte for four and then it's going to be position number one we have a double bond if i were to have a one butanol i would have an alcohol group so it's going to be one of these or of course because your molecules can be twisted around it's perfectly fine to draw it something like this they're the same molecule okay so you can draw it this way too so those are the prefix excuse me the suffixes that indicates the different kinds of functional uh groups that we have and on the previous lecture we kind of go over into a few of these as well what's next well then you have uh prefixes such as di tri tetra penta hexa and so on which i'm not going to go beyond penta one of the couple things that i want to mention is that the most common error that i see is on the two and the four it's die is for two not bi and tetra is for four not quad quad or something like that i think people write that in quite a bit so how does it goes into place well suppose that we have our butane and then we have something like this right so you can see that there's actually two methyl side group that is attached to this butane so what happens is that this is going to be called two comma two dimethyl butane well what if we have a structure that look like this and hopefully you can still see that the longest carbon chain is still four so you can go whatever you want and that's going to be the longest carbon chain there so in this case we have four different kinds of methyl attached to this butane so how do we call this well this is going to be two comma two comma four comma four dash tetra methyl butane okay so that's as simple as that in terms of where the prefixes come in if you have multiple um you put it twice as the number so from the number you can see that this is two two four and four so there's four different stuff here and the tetra is a little bit of a redundancy in terms of how many that you have now there's a couple things that i want to mention here is the structure on how you write down these numbers and dashes you see it's simple enough if you have a number next to another number you put a comma right so because if you were to say 2 2 without the comma in there people won't know is it on position 22 or is it on position 2 and 2. now it's just kind of a bit of redundancy to make sure that there's less confusion and of course there's a dash here and every time you have number and letters you're going to have a dash in between them to make sure that there's a distinction between the two and the last one is that if you write any of the name you don't put any spaces in between them it's just kind of one big lump so the tetramethyl butane all right so that's about it in terms of the prefixes and the common error that i see is a die and a tetra so make sure that remember die is two tetra is four and what else well we also have um the details on the numbering system right um now whenever you have a numbering system you want to have the smallest possible number combination so for example if i were to have something like this right um or i should say let's let's make it a little bit there right let's set that that's a particular molecule well i can start numbering either the molecules in nature kind of flips around and twists around and so on so we always want to make sure that the number is going to be the smallest best now i can go from uh left to right and count this right so let me use different colors so i can go from left to right and give a number that goes one two three four right so that's that's from left to right this number is going to be 4. oops i can erase the last part there or i can also go from the right to the left and then this side chain here instead of having located in position number four it's going to be located on position number two so two is smaller than four smallest numbering so the proper name of this molecule that i just drew is going to be 2-methyl pentane right it's not 4-methylpentane it's 2-methylpentane and then we're going to have another details which that if he has side chains they are going to be arranged alphabetically excluding the prefixes so let's go back to the previous example of our big molecule that we drew earlier right so this is the name of the molecule is going to be three four five triapyl two methyl nonine notice here is that i arrange the ethyl first before the methyl because e comes before m so ethyl comes first before the methyl and it's going to be it doesn't matter what the prefix is here so the tri and the dye the tetra whatever we don't put that into the alphabetical structure right so just kind of a common thing that i want you to note ethyl comes first and then after ethyl if you have a methyl comes next and then after e m then propane right propyl and if you have the fourth one which is butyl butyl is going to be b4e so butyl right so it's always alphabetical of the side chain name so in this case the b before e before m before p and regardless of whether you have a prefix or no prefix you always look at the side chain name when you arrange the name alphabetically and what else i think i'm almost there what else what else what else um oh right so we already kind of went over the numbers and dashes so every time you have numbers and letters you always put a dash in between them and every time you have multiple numbers you put a comma in between and this is going to be the last one which i am not going to cover at all there's what's called a priority groups and i just want to put this in mention to prepare you for for the next portion of your class and there's a thing called the priority group which is that if you have if you have alkene versus an aldehyde the aldehyde is going to have a priority group so you put the number the smallest possible number from the aldehyde or and the aldehyde is also going to have to be placed on the very end now the uh which one have the priority versus one to the next to the next next that's essentially kind of there's there's a higher priority group i'm not going to go into details why this is the case but there's such a thing as priority group um which is why one goes from next to the next but again that's a little bit beyond the scope of our class i will leave that to your organic professor to cover